Bending-resistant ultra-high-strength weathering steel piles and structural foundations

Abstract

A lightweight, ultra-high strength, weathering steel pile for use as a steel foundation in a structure such as a solar device is disclosed herein. The lightweight, ultra-high strength, weathering steel pile comprises a cold-rolled steel pile having a thickness of 2.5 mm or less, the steel pile having a web and a pair of opposing flanges, each flange having a discontinuity formed therein. The steel pile also comprises a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%.

Description

[0001] This patent application claims priority to and the benefit of U.S. Provisional Application No. 62 / 902,825, filed on September 19, 2019, which is incorporated herein by reference. Technical Field

[0002] The present invention relates to a thin cast steel strip, a method for high-friction rolling of the thin cast steel strip, and a steel product produced from the thin cast steel strip by the method. Background Art

[0003] In a twin-roll continuous casting machine, molten metal is introduced between a pair of relatively rotating, internally cooled horizontal casting rolls so that the metal shell solidifies on the surface of the moving casting rolls and is brought together at the roll gap between the casting rolls to produce a solidified cast strip product that is transported downward from the roll gap between the casting rolls. The term "roll gap" is used herein to refer to the overall area where the casting rolls are closest together. Molten metal is poured from a ladle through a metal delivery system including a tundish and a core nozzle located above the roll gap to form a molten metal casting pool supported on the casting surface of the casting rolls above the roll gap and extending along the length of the roll gap. The casting pool is usually confined between refractory side plates or side baffles that are kept in sliding engagement with the end faces of the casting rolls to block the two ends of the casting pool and prevent it from overflowing.

[0004] In order to obtain the desired thickness, the thin steel strip can be passed through a rolling mill to hot roll the thin steel strip. When hot rolling is performed, the thin steel strip is usually lubricated to reduce the roll bite friction, which in turn reduces the rolling load and roll wear and provides a smoother surface finish. Lubrication is used to provide low friction conditions. Low friction conditions refer to the friction coefficient (μ) of the roll bite being less than 0.20. After hot rolling, the thin steel strip undergoes a cooling process. Under low friction conditions, after undergoing a pickling or acid etching process to remove the oxide scale, large original austenite grain boundary depressions are observed on the hot rolled outer surface of the cooled thin steel strip. In particular, although the thin steel strip tested using the color penetration technique appears to have no defects, after the thin steel strip is pickled, the original austenite grain boundaries are acid-etched to form original austenite grain boundary depressions. This acid etching may also cause defect phenomena along the acid-etched original austenite grain boundaries and the resulting depressions. The resulting defects and delaminations (more commonly referred to as delaminations) may extend to a depth of at least 5 microns, and in some cases 5 to 10 microns.

[0005] For purposes of this disclosure, weathering steel is generally a high-strength, low-alloy steel that is resistant to atmospheric corrosion. In the presence of moisture and air, the oxidation rate of low-alloy steel depends on the degree to which the metal surface is exposed to oxygen, moisture, and atmospheric contaminants. When steel oxidizes, an oxide layer is formed, which is commonly referred to as rust. As the oxidation process progresses, the oxide layer forms a barrier that keeps out oxygen, moisture, and contaminants, and the rate of rusting is slowed. For weathering steel, the oxidation process begins in the same way, but the specific alloying elements in the steel produce a stable, protective oxide layer that adheres to the base metal and is much less porous than the oxide layer that typically forms in non-weathering steel. The result is a much lower corrosion rate than ordinary non-weathering structural steel.

[0006] The definition of weathering steel is given in ASTM A606, Standard Specification for High-Strength, Low-Alloy, Hot-Rolled and Cold-Rolled Steel Sheet and Strip with Improved Atmospheric Corrosion Resistance. There are two types of weathering steel: Type 2, which contains at least 0.20% copper (at least 0.18% copper for product inspection) as cast or by hot analysis; and Type 4, which contains additional alloying elements to provide a corrosion index of at least 6.0 calculated in accordance with ASTM G101, Standard Guide for Estimating the Atmospheric Corrosion Resistance of Low-Alloy Steels, and provides a significantly better level of corrosion resistance than carbon steel with or without the addition of copper.

[0007] Prior to the present invention, weathering steels were generally limited to yield strengths of less than 700 MPa and tensile strengths of less than 1000 MPa. Furthermore, prior to the present invention, the strength properties of weathering steels were generally achieved through age hardening. U.S. Pat. No. 10,174,398, incorporated herein by reference, is an example of a weathering steel achieved through age hardening.

[0008] Steels such as G100 steel or Gr70 steel are not well suited for many products, such as piles or steel foundations driven into the ground for use in solar installations and / or the highway industry, such as supporting guardrails, signage, etc., due to strength limitations and corrosion limitations. As used herein, a "solar installation" is a structure used to support solar cells, such as used in a solar farm in a photovoltaic power plant designed to supply power to an electric grid, etc. The corrosive nature of groundwater and soil components requires that the material thickness should be much greater than 2.5 mm to maintain the necessary integrity of these structural members. Therefore, hot-dip galvanized steel is used for these applications. Hot-dip galvanized steel is treated with zinc to increase the corrosion resistance of the underlying material. Therefore, it is common practice in the solar industry to use galvanized 50ksi W6 or W8 I-beam piles as structural piles. However, the zinc coating reacts adversely with groundwater and soil components, resulting in the possibility of contamination of groundwater and soil components. The zinc coating also only provides a limited degree of protection. Once the zinc oxide layer degrades, metallic oxidation of the zinc coating may still degrade the structural integrity of the underlying material and / or require increased material thickness to maintain the necessary integrity of these structural members. Summary of the invention

[0009] Therefore, the present disclosure is intended to provide a pile or steel foundation design made of lightweight ultra-high strength weathering steel to replace the existing materials that the pile or steel foundation relies on. Specifically, the present disclosure is intended to provide a lightweight pile or steel foundation having a shape formed by a thin cast metal strip. The shape of the present disclosure is intended to increase the strength and durability of the pile or steel foundation so that it can withstand the deformation caused by the force required to drive the structural member into the ground, and / or be used as a structural member of an above-ground external structure such as a solar device, a guardrail, a signboard, etc. In particular, the present disclosure is intended to provide a pile or steel foundation formed by cold rolling a thin cast steel strip having a thickness of 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less, or a pile or steel foundation cast into a thin cast steel shape having a material thickness of 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less. The pile or steel foundation is made of a thin cast steel strip that is cold rolled using one or more rolling stands. In addition, through holes, slots and / or welds can also be achieved by relying on a stamping system, a CNC plasma system and / or a rolling system, etc., as described below. The present disclosure also aims to provide a pile or steel foundation formed by cold rolling of a thin cast steel strip, which does not require a separate application of a protective coating, such as a zinc coating provided on a hot-dip galvanized structural member. The "separately applied coating" used in this article is a protective coating, which can be a surface protective layer independent of the composition of the steel. Examples of such separately applied protective coatings include zinc coatings, electroplated zinc layers (such as hot-dip galvanized layers), anti-aluminum silicon corrosion coatings, etc. More importantly, as described below, the piles or steel foundations of the present disclosure produce corrosion resistance without the need for a separately applied coating. By definition, the ultra-high strength weathering steel disclosed herein inherently has the necessary corrosion resistance without relying on hot-dip galvanizing. Therefore, the weathering steel of the present disclosure does not need or have a zinc coating, a hot-dip galvanized layer, etc., and will not be galvanized.

[0010] In one set of examples, the present disclosure is directed to providing a lightweight ultra-high strength weathering steel formed by moving the peritectic point away from the carbon zone and / or increasing the transformation temperature of the peritectic point of a composition. Specifically, moving the peritectic point away from the carbon zone and / or increasing the transformation temperature of the peritectic point of a composition appears to suppress defects and result in defect-free high-strength martensitic steel sheet. In this case, nickel addition is relied upon for this purpose, wherein the amount of nickel added must be sufficient to move the "peritectic point" away from the carbon zone, whereas in the same composition without the addition of nickel, the peritectic point exists in the carbon zone. The present invention also discloses a product produced by the ultra-high strength weathering steel in various shapes additionally disclosed herein, and the product has improved strength characteristics not previously available.

[0011] In another set of examples, the present disclosure is directed to eliminating prior austenite grain boundary depressions, but maintaining a smoothed pattern. In this set of examples, the thin cast steel strip is subjected to high friction rolling conditions, wherein the grain boundary depressions form a smoothed pattern at least at the surface of the thin cast steel strip. Specifically, this example is directed to forming a smoothed pattern of prior austenite grain boundary depressions while eliminating prior austenite grain boundary depressions from the surface and improving the formability of the steel strip or steel product. By improving the formability of steel strip products having a variety of shapes additionally disclosed herein, and achieving improved strength properties, previously unattainable steel strip products are now possible. This example is applicable not only to the ultra-high strength weathering steels described above, but also to martensitic steels, other weathering steels, and / or steel strips or products exhibiting prior austenite grain boundary depressions.

[0012] In another set of examples, the present disclosure is directed to eliminating grain boundary depressions and the smeared pattern formed thereby. In this set of examples, the thin cast steel strip undergoes surface homogenization to eliminate the smeared pattern. As a result, the surface of the thin cast steel strip is not only free of prior austenite grain boundary depressions, but also free of the smeared pattern produced by high friction rolling conditions, thereby providing a thin cast steel strip surface having a surface roughness (Ra) of no more than 2.5 microns in some examples. These examples are applicable not only to the ultra-high strength weathering steels described above, but also to martensitic steels, other weathering steels, and / or steel strips or products exhibiting prior austenite grain boundary depressions.

[0013] Ultra-high strength weathering steel

[0014] First, the present invention discloses a lightweight ultra-high strength weathering steel plate made by the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; b) solidifying at a heat flux greater than 10.0 MW / m2 into a steel sheet having a thickness of less than or equal to 2.5 mm, and cooling the steel sheet to a temperature less than 1080°C and greater than the Ar3 temperature in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec before rapid cooling and / or before hot rolling (if hot rolling is used); and (c) rapid cooling to form a steel sheet having a microstructure comprising at least 75 volume % martensite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa and an elongation of 1% to 10%.

[0015] Here and elsewhere in the present disclosure, elongation refers to total elongation. "Rapid cooling" refers to cooling to 100 to 200°C at a rate of more than 100°C / second. Rapid cooling of the composition of the present invention while adding nickel can obtain a steel strip containing up to 95% or more of a martensitic phase. In one example, rapid cooling forms a steel plate having a microstructure containing at least 95% by volume of martensite. The amount of nickel added must be sufficient to move the "peritectic point" away from the carbon zone, while in the same composition without the addition of nickel, the peritectic point exists in the carbon zone. Specifically, the inventors believe that the inclusion of nickel in the composition helps to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point of the composition, which appears to suppress defects and produce defect-free high-strength martensitic steel plates. In one example, the lightweight ultra-high strength weathering steel plate can also be hot rolled to a rolling reduction of 15% to 50% before rapid cooling.

[0016] In order to suppress the peritectic cracking of the steel sheet, the carbon content in the steel sheet of the present invention is preferably not less than 0.20%. Nickel is added to further suppress the peritectic cracking of the steel sheet, but this does not rely solely on the carbon component. The effect of nickel on the corrosion index is reflected in the following formula for determining the corrosion index calculation: copper*26.01+nickel*3.88+chromium*1.2+silicon*1.49+phosphorus*17.28-copper*nickel*7.29-nickel*phosphorus*9.1-copper*copper*33.39 (where each element is calculated by weight percentage).

[0017] The melt may be solidified into a steel plate having a thickness of less than 2.5 mm at a heat flux greater than 10.0 MW / m2, and the steel plate may be cooled to a temperature less than 1080°C and greater than the Ar3 temperature in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec before rapid cooling and / or before hot rolling (if hot rolling is used). The non-oxidizing atmosphere is an atmosphere generally composed of an inert gas (e.g., nitrogen, argon, or a mixture thereof) containing less than about 5% oxygen by weight. In another example, the steel plate may be cooled to a temperature less than 1100°C and greater than the Ar3 temperature in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec before rapid cooling and / or before hot rolling (if hot rolling is used).

[0018] In some examples, the martensite in the steel plate may be formed from austenite grains having a grain size greater than 100 microns. In other examples, the martensite in the steel plate may be formed from austenite grains having a grain size greater than 150 microns.

[0019] The steel sheet is rapidly cooled to form a steel sheet having a microstructure comprising at least 75 volume % martensite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In other examples, the steel sheet is rapidly cooled to form a steel sheet having a microstructure comprising at least 75 volume % martensite plus bainite. In a specific example, the rapid cooling forms a steel sheet having a microstructure comprising at least 95 volume % martensite plus bainite.

[0020] In some examples, the steel plate may be hot rolled to a reduction of 15% to 35% prior to rapid cooling. In other examples, the steel plate may be hot rolled to a reduction of 15% to 50% prior to rapid cooling.

[0021] The molten steel used to produce the ultra-high strength weathering steel plate is a silicon-killed steel (i.e., silicon-deoxidized steel) containing 0.10 wt% to 0.50 wt% silicon. The steel plate may also contain less than 0.008 wt% aluminum or less than 0.006 wt% aluminum. The melt may have a free oxygen content of 5 to 70 ppm or 5 to 60 ppm. The steel plate may have a total oxygen content greater than 50 ppm. The inclusions include MnOSiO2, typically 50% of the inclusions have a particle size of less than 5 microns, and the inclusions are likely to enhance the evolution of the microstructure, thereby enhancing the mechanical properties of the strip.

[0022] The present invention also discloses a method for manufacturing a lightweight ultra-high strength weathering steel plate, the method comprising the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; (b) forming the melt into a casting surface supported on a pair of cooling casting rolls; A casting pool, wherein a pair of cooling casting rolls are provided with a roll gap therebetween; (c) rotating the casting rolls relative to each other and solidifying the melt at a heat flux greater than 10.0 MW / m2 to produce a steel plate having a thickness of less than 2.5 mm, and cooling the steel plate to a temperature less than 1080°C and greater than the Ar3 temperature in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec before rapid cooling and / or before hot rolling (when hot rolling is used); and (d) rapid cooling to form a steel plate having a microstructure comprising at least 75% martensite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In a specific example, the rapid cooling forms a steel plate having a microstructure comprising at least 95% by volume martensite plus bainite. Before rapid cooling and / or before hot rolling (in the case of hot rolling), the steel plate may be cooled to a temperature below 1100°C and above the Ar3 temperature at a cooling rate of more than 15°C / second in a non-oxidizing atmosphere. The carbon content of the steel plate composition cannot be less than 0.20% because it does not work to suppress the peritectic cracking of the steel plate. In one example, the light ultra-high strength weathering steel plate may be hot rolled to a rolling reduction of 15% to 50% before rapid cooling.

[0023] Furthermore, the method of manufacturing a lightweight ultra-high strength weathering steel plate may include the step of tempering the steel plate at a temperature of 150° C. to 250° C. for 2 to 6 hours.

[0024] The melt may have a free oxygen content of 5 to 70 ppm or 5 to 60 ppm. The steel plate may have a total oxygen content greater than 50 ppm. The melt may be solidified into a steel plate having a thickness of less than 2.5 mm at a heat flux greater than 10.0 MW / m2, and the steel plate may be cooled to a temperature less than 1080°C and greater than the Ar3 temperature at a cooling rate greater than 15°C / second in a non-oxidizing atmosphere before rapid cooling and / or before hot rolling (in the case of hot rolling). In another example, the steel plate may be cooled to a temperature less than 1100°C and greater than the Ar3 temperature at a cooling rate greater than 15°C / second in a non-oxidizing atmosphere before rapid cooling and / or before hot rolling (in the case of hot rolling).

[0025] In some embodiments, the martensite in the steel sheet may be derived from austenite grains having a grain size greater than 100 microns. In other embodiments, the martensite in the steel sheet may be derived from austenite grains having a grain size greater than 150 microns.

[0026] The method for manufacturing a lightweight ultra-high strength weathering steel plate may also include hot rolling the steel plate to a rolling reduction of 15% to 35%, and then rapidly cooling to form a steel plate having a microstructure comprising at least 75% by volume of martensite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In some embodiments, the method for manufacturing a lightweight ultra-high strength steel plate may also include hot rolling the steel plate to a rolling reduction of 15% to 50%, and then rapidly cooling to form a steel plate having a microstructure comprising at least 75% by volume of martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In addition, the method for manufacturing a hot-rolled light-gauge ultra-high-strength steel plate may include hot rolling the steel plate to a rolling reduction of 15% to 35%, and then rapidly cooling to form a steel plate having a microstructure comprising at least 75% by volume of martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In the above specific example, the steel plate is hot rolled and then rapidly cooled to form a steel plate having a microstructure comprising at least 95% by volume of martensite plus bainite.

[0027] The present invention also discloses a steel pile, which includes a web and one or more flanges cold-rolled from a carbon alloy steel plate, wherein the composition of the carbon alloy steel plate includes, by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is a silicon-killed steel containing less than 0.01% aluminum, wherein the carbon alloy steel plate has a microstructure containing at least 75 volume % of martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, an elongation of 1% to 10%, and a corrosion index of 6.0 or higher.

[0028] High friction rolled high strength weathering steel

[0029] Secondly, in a set of examples, the present invention discloses a carbon alloy thin cast steel strip having a cast thickness of less than or equal to 2.5 mm. These examples are applicable not only to the ultra-high strength weathering steels mentioned above, but also to martensitic steels, other weathering steels and / or steel strips or products exhibiting original austenite grain boundary depressions. The carbon alloy thin cast steel strip may contain 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel by weight, and is a silicon-killed steel containing less than 0.01% aluminum, and contains the remainder of iron and impurities caused by melting. After high friction hot rolling, the thickness of the carbon alloy thin cast steel strip is reduced by 15% to 50% compared with the cast thickness. The hot rolled steel strip comprises a pair of opposing high friction hot rolled surfaces that are substantially free, essentially free or free of prior austenite grain boundary depressions and have a smeared pattern. In some embodiments, the steel strip comprises a microstructure having at least 75 volume % martensite or at least 75 volume % martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In some instances, the steel strip is a weathering steel having a corrosion index of 6.0 or higher.

[0030] In some examples, the pair of opposing high friction hot rolled surfaces are substantially free of prior austenite grain boundary depressions. In some examples, the pair of opposing high friction hot rolled surfaces are substantially free of prior austenite grain boundary depressions.

[0031] The present invention also discloses a method for manufacturing a hot-rolled carbon alloy steel strip, which contains by weight 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains the balance of iron and impurities caused by melting, the method comprising the following steps:

[0032] (a) preparing a molten steel melt;

[0033] (b) forming the melt into a casting pool supported on casting surfaces of a pair of cooled casting rolls with a nip defined therebetween;

[0034] (c) causing the casting rolls to rotate relative to each other and solidifying the melt at a heat flux greater than 10.0 MW / m2 into a steel strip having a thickness of less than or equal to 2.5 mm conveyed downwardly from the roll gap, and cooling the steel strip in a non-oxidizing atmosphere at a cooling rate greater than 15°C / second to a temperature less than 1080°C and greater than the Ar3 temperature;

[0035] (d) high friction hot rolling of a thin cast steel strip to a hot rolled thickness that is 15% to 50% less than the as-cast thickness, producing a hot rolled steel strip having substantially no, essentially no or no prior austenite grain boundary depressions and having a smeared pattern.

[0036] The high friction hot rolled thin cast steel strip having substantially no, essentially no or no prior austenite grain boundary depressions and having a smeared pattern may be a weathering steel having a corrosion index of 6.0 or higher. In addition, the high friction hot rolled steel strip may include a microstructure having at least 75 volume % martensite or at least 75 volume % martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%.

[0037] High-friction rolling of high-strength martensitic steel

[0038] Third, in another set of examples, the present invention discloses a carbon alloy thin cast steel strip, which includes a pair of relative high friction hot rolled surfaces, which are surface homogenized after being high friction rolled. These examples are not only applicable to the above-mentioned ultra-high strength weathering steel, but also to martensitic steel, other weathering steel and / or steel strips or products exhibiting original austenite grain boundary depressions. After being surface homogenized, the pair of relative high friction hot rolled surfaces do not have the smoothed grain boundary depressions previously formed by the high friction rolling process. In some embodiments, the carbon alloy thin cast steel strip may also include a microstructure having at least 75 volume % martensite or at least 75 volume % martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In some embodiments, the steel strip includes a microstructure having at least 90 volume % martensite or at least 90 volume % martensite plus bainite. In some embodiments, the steel strip includes a microstructure having at least 95 volume % martensite or at least 95 volume % martensite plus bainite.

[0039] Exemplary homogenized steel strip within the scope of the present disclosure may include, by weight, 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon killed steel with less than 0.01% aluminum, and the balance is iron and impurities resulting from melting.

[0040] The present invention also discloses a method for manufacturing a hot-rolled carbon alloy steel strip. The method may include the following steps:

[0041] (a) preparing a molten steel melt;

[0042] (b) forming the melt into a casting pool supported on casting surfaces of a pair of cooled casting rolls with a nip defined therebetween;

[0043] (c) causing the casting rolls to rotate relative to each other and solidifying the melt at a heat flux greater than 10.0 MW / m2 into a steel strip having a thickness of less than or equal to 2.5 mm conveyed downwardly from the roll gap, and cooling the steel strip in a non-oxidizing atmosphere at a cooling rate greater than 15°C / second to a temperature less than 1080°C and greater than the Ar3 temperature;

[0044] (d) high friction rolling of a thin cast steel strip to a hot rolled thickness that is 15% to 50% less than the as-cast thickness, producing a hot rolled steel strip free of prior austenite grain boundary pits and having a smeared pattern; and

[0045] (e) performing surface homogenization on the high friction hot rolled steel strip to eliminate the smear pattern.

[0046] The high friction hot rolled homogenized thin steel strip may include a microstructure having at least 75% by volume of martensite or at least 75% by volume of martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%, thereby providing a high strength martensitic steel. In addition, the high friction hot rolled homogenized steel strip may contain 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel by weight, and is a silicon-killed steel containing less than 0.01% aluminum, and contains the balance of iron and impurities caused by melting.

[0047] The present disclosure also describes how to utilize the thin cast steel strip, the above composition, and / or the above properties as described above to produce an ultra-high strength weathering steel pile. Specifically, in one example, the ultra-high strength weathering steel pile includes a plurality of side walls, each side wall having a thickness of approximately 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less. The pile can be formed from a steel strip. Specifically, the pile can be formed from a cast steel strip. The pile can be formed from a hot rolled cast steel strip. In addition, the pile can be cold rolled. The composition of the pile may include by weight 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains the balance of iron and impurities caused by melting. The pile may also include or have a corrosion index of 6.0 or more, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and / or an elongation of 1% to 10%.

[0048] In some examples, the composition of the pile includes a nickel content sufficient to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point to form a carbon alloy steel strip having a microstructure of at least 75 volume % martensite or martensite plus bainite. In some examples, the pile can be formed from a steel strip, wherein the steel strip has a hot rolled thickness reduced by 15% to 50% from the as-cast thickness after being hot rolled. The hot rolled material can be high friction rolled to provide a high friction rolled thickness.

[0049] Various features and shapes of ultra-high strength weathering steel are further described herein. These features may be provided in combination or independently of one another. In some examples, the ultra-high strength weathering steel pile may be a C-shaped slot pile, wherein the multiple side walls are a web and one or more flanges. More specifically, the ultra-high strength weathering steel pile may be a curled C-shaped slot pile and / or a corrugated C-shaped slot pile, wherein the multiple side walls are a web and one or more flanges. In some examples, the ultra-high strength weathering steel pile may be a tube, wherein the multiple side walls form a tube. More specifically, the ultra-high strength weathering steel pile may be a square tube or a rectangular tube. In addition, the ultra-high strength weathering steel pile may generally be a square tube or a rectangular tube, wherein one or more of the multiple side walls further include one or more corrugations. The multiple side walls do not include a coating applied separately. The multiple side walls are not galvanized. At least one of the multiple side walls may be a curled edge. More specifically, one or more flanges of the curled C-shaped slot pile may be a single curled edge. The first layer and the second layer of each curled edge of the one or more flanges may be fixed together by one or more welds. The first layer of the one or more flanges may transition to the second layer via a teardrop transition. Alternatively or additionally, at least one of the plurality of sidewalls may include one or more corrugations. In some examples, the web of the C-channel pile may include one or more corrugations. Alternatively or additionally, the one or more flanges of the C-channel pile may include one or more corrugations.

[0050] More specifically, the ultra-high strength weathering steel pile may include a web and a pair of opposing flanges, wherein each flange has one or more discontinuous portions formed therein. In one example, the web may include a discontinuous portion in the form of a V-shaped transition. The V-shaped transition may be located in the center of the web relative to the height of the pile. Such a pile may be referred to as an M-groove pile. Alternatively or additionally, one or both of the flanges in the pair of opposing flanges may include a discontinuous portion in the form of a V-shaped transition. The V-shaped transition portion of the flange may be located in the center of the flange relative to the width of the pile. In some examples, the discontinuous portion may be one or more arc-shaped corrugations. The arc may be a true arc. Alternatively, the arc may include one or more flat portions. The one or more flat portions may be at least 1 times the thickness of the material. In one example, the web may include two corrugations that are arc-shaped and are evenly spaced on the web relative to the height of the pile. Alternatively or additionally, one or both of the flanges in the pair of opposing flanges may include one or more arc-shaped corrugations. In each of the above examples, one or both of the pair of opposing flanges may include a folded-back lip. The folded-back lip may be folded back at an angle inclined relative to the web and the corresponding flange. In the above examples of the height of the ultra-high strength weathering steel pile, the extended height of the web of the pile may be 4 to 12 inches, and the extended width of each of the pair of opposing flanges of the pile may be 2 to 8 inches. In other examples of the above ultra-high strength weathering steel pile, the height of the ultra-high strength weathering steel pile may be 2 to 14 inches, and its width may be 1 to 10 inches.

[0051] In some examples, the ultra-high strength weathering steel pile comprises a thickness of approximately 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less. The pile may be formed from a thin cast steel strip that is cold-rolled into a steel pile having multiple sidewalls and a corrosion index of 6.0 or greater. The ultra-high strength weathering steel pile may also include a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. The composition of the ultra-high strength weathering steel pile may include a nickel content sufficient to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point to form a carbon alloy steel strip having a microstructure of at least 75 volume % martensite or martensite plus bainite. In one example, the material composition of the ultra-high strength weathering steel pile includes, by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains the balance of iron and impurities caused by melting.

[0052] A solar device is also discussed herein. The solar device may include an ultra-high strength weathering steel pile, which includes a plurality of side walls and / or webs and a pair of opposing flanges, wherein each flange has one or more discontinuous portions formed therein, and each side wall, web, and flange may have a thickness of approximately 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less. The ultra-high strength weathering steel pile of the solar device may contain 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel by weight, and is silicon-killed steel containing less than 0.01% aluminum, and contains the balance of iron and impurities caused by melting. The ultra-high strength weathering steel piles of the solar device may include a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In this example, a portion of the length of the ultra-high strength weathering steel pile is driven into the ground, and one or more solar cells are supported above the ground by the ultra-high strength weathering steel piles. Therefore, the ultra-high strength weathering steel piles of the solar device may additionally or alternatively have many of the features described above and in the remainder of this disclosure.

[0053] The examples of the ultra-high strength weathering steel piles can also be stored and / or transported in a nested arrangement. The nested arrangement of the ultra-high strength weathering steel piles can include a row of steel piles having first, second and third steel piles, each steel pile including a web and a pair of opposing flanges, each flange having a discontinuous portion formed therein, wherein one flange of the pair of opposing flanges of the first steel pile overlaps and interlocks with one flange of the pair of opposing flanges of the second steel pile, and one flange of the pair of opposing flanges of the third steel pile overlaps and interlocks with another flange of the pair of opposing flanges of the second steel pile. The nested arrangement can also include a second row of steel piles having fourth, fifth and sixth steel piles, each steel pile including a web and a pair of opposing flanges, each flange having a discontinuous portion formed therein, wherein the fourth, fifth and sixth steel piles are arranged in a similar manner to the first, second and third steel piles, respectively, and are stacked on top of the first, second and third steel piles to form two rows of stacked forms. In some examples, the nested arrangement may include a plurality of rows each having a plurality of piles, such as at least five rows each consisting of a plurality of steel piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention will be more fully described and explained below with reference to the accompanying drawings, in which:

[0055] Figure 1 A strip casting plant incorporating an on-line hot rolling mill and a coiler is shown.

[0056] Figure 2 Details of a twin-roll strip caster are shown.

[0057] Figure 3 is a micrograph of a steel plate having a microstructure comprising at least 75% martensite.

[0058] Figure 4 is a phase diagram showing the effect of nickel in moving the peritectic point away from the carbon region.

[0059] Figure 5 is a flow diagram of a process of one or more aspects of the present disclosure.

[0060] Figure 6 3 is an image showing the morphology of the surface of a hot-rolled steel strip under high friction conditions after surface leveling treatment.

[0061] Figure 7 is an image showing the surface of a hot rolled steel strip in high friction conditions with a smeared pattern that has not been homogenized.

[0062] Figure 8 It is a friction coefficient model diagram used to determine the friction coefficient of a specific pair of working rolls, the specific rolling force and the corresponding rolling reduction.

[0063] Fig. 9 It is the continuous cooling transformation (CCT) diagram of steel.

[0064] Fig.10 is a cross-sectional view of a rolled C-channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0065] Fig.11 yes Fig.10 A perspective view of a pile or steel foundation cold-formed from a thin cast steel strip is shown in accordance with one or more aspects of the present disclosure.

[0066] Fig.12 is a cross-sectional view of a corrugated C-channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0067] Fig.13 is a cross-sectional view of a corrugated C-channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0068] Fig.14 is a cross-sectional view of a square tube with a reinforcement member for a steel pile or steel foundation formed by cold rolling from a thin cast steel strip according to one or more aspects of the present disclosure.

[0069] Fig.15is a cross-sectional view of a rectangular tube with reinforcement members for a steel pile or steel foundation cold-formed from a thin cast steel strip according to one or more aspects of the present disclosure.

[0070] Fig.16 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0071] Fig.17 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0072] Fig.18 is a cross-sectional view of an M-shaped channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0073] Fig.19 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0074] Fig. 20 is a cross-sectional view of a C-channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0075] Fig.21 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0076] Fig. 22 is a cross-sectional view of a C-channel shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0077] Fig.23 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0078] Fig.24 It is a test result diagram of the lightweight ultra-high strength weathering steel pile material disclosed in the present invention.

[0079] Fig.25 is a reproduction of the top side of a UHSW steel pile of the present disclosure driven into the ground.

[0080] Fig.26 is a reproduction of the top side of a prior art wide flange beam driven into the ground.

[0081] Fig. 27 It is a schematic diagram of the allowable point load at the free end of a fixed cantilever in the case of a pile or structural foundation.

[0082] Fig.28 It is a schematic diagram of the free end deflection under the allowable point load for an example of a pile or structural foundation.

[0083] Fig.29is a cross-sectional view of the shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0084] Fig.30 is a cross-sectional view of the shape of a pile or steel foundation cold-formed from a thin cast steel strip in accordance with one or more aspects of the present disclosure.

[0085] Fig.31 An example of a nested arrangement of steel piles or steel foundations of the present disclosure is shown. DETAILED DESCRIPTION

[0086] In one example, a lightweight ultra-high strength weathering steel plate is described herein. The lightweight ultra-high strength weathering steel plate can be made from a molten melt. The molten melt can be processed by a twin-roll continuous casting machine. In one example, the lightweight ultra-high strength weathering steel plate can be made by the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; (b) at a temperature above 10.0 MW / m2 heat flux solidification, produce a steel plate with a thickness of less than 2.5 mm, and before rapid cooling and / or before hot rolling (in the case of hot rolling), the steel plate is cooled to a temperature below 1080°C and above the Ar3 temperature at a cooling rate of greater than 15°C / second in a non-oxidizing atmosphere; and (c) rapid cooling to form a steel plate having a microstructure comprising at least 75 volume % of martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In one example, the lightweight ultra-high strength weathering steel plate may also be hot rolled to a rolling reduction of 15% to 50% before rapid cooling. Before rapid cooling and / or before hot rolling (in the case of hot rolling), the steel plate may be cooled to a temperature below 1100°C and above the Ar3 temperature at a cooling rate of greater than 15°C / second in a non-oxidizing atmosphere. The Ar3 temperature is the temperature at which austenite begins to transform into ferrite during cooling. In other words, the Ar3 temperature is the austenite transformation point. In each instance, nickel moves the peritectic point away from the carbon zone and / or increases the transformation temperature of the peritectic point of the steel plate composition to provide a defect-free steel plate. The effect of nickel on the corrosion index is reflected in the following formula used to determine the corrosion index calculation: copper*26.01+nickel*3.88+chromium*1.2+silicon*1.49+phosphorus*17.28–copper*nickel*7.29–nickel*phosphorus*9.1–copper*copper*33.39 (where each element is measured by weight percentage).

[0087] Also described herein is a thin cast steel strip having hot rolled outer side surfaces characterized in that these surfaces are substantially free, essentially free or free of prior austenite grain boundary depressions, but have a smeared pattern or an elongated surface structure, such as in the case of high-friction rolled high-strength martensitic steels. Also described herein is a method or process for producing said thin cast steel strip. These examples are applicable not only to the ultra-high strength weathering steels described above, but also to martensitic steels, other weathering steels and / or steel strips or products exhibiting prior austenite grain boundary depressions.

[0088] Also described herein is a thin steel strip having hot rolled outer side surfaces characterized in that these surfaces are substantially free, essentially free or free of prior austenite grain boundary depressions and are free of smear patterns or elongated surface structures, such as in the case of high-friction rolled high-strength weathering steels. Also described herein is a method or process for producing said thin cast steel strip. These examples are applicable not only to the ultra-high strength weathering steels described above, but also to martensitic steels, other weathering steels and / or steel strips or products exhibiting prior austenite grain boundary depressions.

[0089] As used herein, "substantially free" means that less than 50% of each relative hot rolled outer side surface contains prior austenite grain boundaries or prior austenite grain boundary depressions after acid etching (pickling). "At least substantially free" of all prior austenite grain boundaries or prior austenite grain boundary depressions means that 10% or less of each relative hot rolled outer side surface contains prior austenite grain boundaries or prior austenite grain boundary depressions after acid etching (pickling). After acid etching (also known as pickling), the depressions form eroded grain boundary depressions, so that the prior austenite grain boundaries are visible at 250 times magnification. In other cases, "free" means that each relative hot rolled outer side surface is free of (i.e., completely free of) prior austenite grain boundary depressions, which includes the absence of any prior austenite grain boundary depressions after acid etching. It should be emphasized that after hot rolling, when the grain boundary depressions and delaminations on the surface are removed using the techniques described in this article (for example, when hot rolling is carried out at a temperature above the Ar3 temperature using a roll bite friction coefficient equal to or greater than 0.20), the original austenite grain boundaries may still exist inside the strip.

[0090] Figure 1 and Figure 2The sequential arrangement of parts of a strip casting machine for continuously casting steel strip or steel plate of the present invention is shown. The twin-roll continuous casting machine 11 can continuously produce a cast steel strip 12, which passes through a guide table 13 in a conveying path 10 to a pinch roll stand 14 having a pinch roll 14A. After leaving the pinch roll stand 14, the strip immediately enters a hot rolling mill 16 having a pair of working rolls 16A and a support roll 16B, in which the cast strip is hot rolled to reduce the required thickness. The hot rolled strip is transferred to an output table 17, on which the strip enters an intensive cooling section through a water sprayer 18 (or other appropriate device). The rolled and cooled strip then passes through a pinch roll stand 20 including a pair of pinch rolls 20A, and then reaches a coiler 19.

[0091] like Figure 2 As shown, the twin roll continuous casting machine 11 includes a main frame 21 that supports a pair of laterally arranged casting rolls 22 having casting surfaces 22A. During the casting operation, molten metal is supplied from a ladle (not shown) to a tundish 23, through a refractory cover 24 to a distributor or mobile tundish 25, and then from the distributor or mobile tundish 25 through a metal delivery nozzle 26 between the casting rolls 22 above the roll gap 27. The molten metal delivered between the casting rolls 22 forms a casting pool 30 above the roll gap supported on the casting rolls. The casting pool 30 is confined to the ends of the casting rolls by a pair of side cofferdams or baffles 28, which can be pushed toward the ends of the casting rolls by a pair of pushers (not shown), which include hydraulic cylinder units (not shown) connected to the side baffle supports. The upper surface of the casting pool 30 (commonly referred to as the "meniscus" liquid level) is generally higher than the lower end of the delivery nozzle, so that the lower end of the delivery nozzle is immersed in the casting pool 30. The casting rolls 22 are internally water cooled so that the shell solidifies on the moving surfaces of the casting rolls 22 as they pass through the casting pool and converges together at the nip 27 between the casting rolls 22 to produce the cast steel strip 12 which is conveyed downwardly from the nip between the casting rolls.

[0092] The twin roll continuous casting machine may be of the type shown and described in detail in U.S. Patent Nos. 5,184,668, 5,277,243, 5,488,988 and / or U.S. Patent Application No. 12 / 050,987, disclosed in U.S. Patent Publication No. 2009 / 0236068A1. These patents and publications are incorporated herein by reference. Reference is made to these patents and publications to illustrate appropriate structural details of the twin roll continuous casting machine that may be used in examples of the present invention.

[0093] Using any desired process (e.g., in combination with Figure 1 and Figure 2After forming (casting) a thin steel strip by the strip casting process described above, the strip may be hot rolled and cooled to form a desired thin steel strip having opposite hot rolled outer sides that are at least substantially free, essentially free, or free of prior austenite grain boundary depressions. Figure 1 As shown, the in-line hot rolling mill 16 reduces the size of the strip from the caster by 15% to 50%. On the delivery station 17, the cooling may include a water cooling section to control the cooling rate of the austenite transformation to obtain the desired microstructure and material properties.

[0094] Figure 3 A micrograph of a steel plate having a microstructure comprising at least 75% martensite, the martensite being composed of original austenite grains having a grain size of at least 100 micrometers is shown. In some examples, the steel plate is rapidly cooled to form a steel plate having a microstructure comprising at least 90 volume % martensite or martensite and bainite. In another example, the steel plate is rapidly cooled to form a steel plate having a microstructure comprising at least 95 volume % martensite or martensite and bainite. In each of these examples, the steel plate may be additionally hot rolled to a reduction of 15% to 50% prior to rapid cooling.

[0095] Please refer to Figure 1 , wherein a high temperature box 15 is shown. Figure 1 As shown, after the strip is formed, the strip may enter an environmentally controlled box called a hot box 15, where the strip continues to passively cool, before being hot rolled to final specifications by a hot rolling mill 16. The strip is maintained in the environmentally controlled box with a protective atmosphere until entering the hot rolling mill 16. In the hot box, the strip moves on a guide table 13 to a pinch roll stand 14. In the example of the present disclosure, undesirable thermal corrosion may occur in the hot box 15. Depending on whether thermal corrosion occurs in the hot box, the strip may be hot rolled under high friction rolling conditions based on parameters defined in more detail below.

[0096] In certain cases, the method of forming the thin steel strip also includes hot rolling the thin steel strip using a pair of opposing work rolls, the friction coefficient (μ) of the work rolls being high enough to enable the opposing hot rolled outer side surfaces of the thin steel strip to be substantially free of, essentially free of, or free of prior austenite grain boundary depressions and to have an elongated surface structure associated with a surface smear pattern formed by plastic deformation under shear. In certain cases, the pair of opposing work rolls produces a friction coefficient (μ) equal to or greater than 0.20, 0.25, 0.268, or 0.27 at a temperature above the Ar3 temperature with or without the use of a lubricant. It should be understood that the friction coefficient can be increased by increasing the surface roughness of the work roll surface, eliminating the use of any lubricant, reducing the amount of lubricant used, and / or selecting a specific type of lubricant for use. Other mechanisms known to those of ordinary skill in the art for increasing the friction coefficient may also be used in combination with the aforementioned mechanisms or independently of the aforementioned mechanisms. The above process is generally referred to herein as high friction rolling.

[0097] As described above, it should be understood that the high friction rolling can be achieved by increasing the surface roughness of one or more work rolls. This is generally referred to as work roll surface texturing in this article. The surface texture of the work roll can be modified and measured by various parameters for high friction rolling applications. For example, the average roughness (Ra) of the profile of the work roll can provide a reference point for generating the necessary friction coefficient of the roll bite mentioned in the above example. In order to achieve high friction rolling by work roll surface texturing, in one example, the newly ground and textured work roll may have an Ra between 2.5 microns and 7.0 microns. The newly ground and textured work roll is more generally referred to as a new work roll in this article. In a specific example, the Ra of the new work roll may be between 3.18 microns and 4.0 microns. The average roughness of the new work roll will decrease during use or after wear. Therefore, in one example, the old work roll can also be used to produce the above-mentioned high friction rolling conditions, as long as the Ra of the old work roll is between 2.0 microns and 4.0 microns. In one particular example, the old work rolls may have an Ra between 1.74 microns and 3.0 microns while still achieving the high friction rolling conditions described above.

[0098] Alternatively or additionally, the average surface roughness depth (Rz) of the profile of the work roll may also be used as an indicator for achieving the above-mentioned high friction rolling conditions. The new work roll may have an Rz between 20 microns and 41 microns. In a specific example, the new work roll may have an Rz between 21.90 microns and 28.32 microns. In an example, for the above-mentioned high friction rolling conditions, the old work roll can be used as long as the old work roll maintains an Rz between 10 microns and 20 microns before being discontinued. In a specific example, the old work roll has an Rz between 13.90 microns and 20.16 microns before being discontinued.

[0099] In addition, the above parameters can also be defined by the average spacing (Sm) between the peaks on the profile. The new work rolls for producing high friction rolling conditions may include Sm between 90 microns and 150 microns. In a specific example, the new work rolls for producing high friction rolling conditions include Sm between 96 microns and 141 microns. In one example, for the above high friction rolling conditions, the old work rolls can be used as long as the old work rolls maintain Sm between 115 microns and 165 microns.

[0100] Table 1 below shows measured test data of the work roll surface textures relied upon to produce high friction rolling conditions by position on the work roll, and also provides a comparison between new work roll parameters and old work roll parameters before being taken out of service:

[0101]

[0102] *“OS Qtr” is the operator side quarter region; “Avg” is the average value **“Ctr” is the center of the band; “Avg” is the average value

[0103] ***“DS Qtr” is the drive side quarter area; “Avg” is the average

[0104] Determining whether high friction rolling is applicable to the examples of the present disclosure may depend on whether hot corrosion occurs in the high temperature box. Hot corrosion is a byproduct or consequence of the casting process, which exposes the original austenite grain boundary depressions on the surface of the steel strip. As described above, in further acid etching, the original austenite grain boundary depressions are easily caused along the eroded original austenite grain boundary depressions to cause the above-mentioned defect phenomenon. Specifically, when the steel is exposed to high temperature in an inert atmosphere (such as a high temperature box), hot corrosion reveals the original austenite grain boundary depressions in the steel strip by forming grooves at the intersection of the original austenite grain boundary depressions and the surface. These grooves make the original austenite grain boundary depressions visible at the surface. Therefore, the examples of the present process determine high friction rolling as a step to produce the desired steel properties during hot corrosion in a high temperature box. Regardless of the presence of hot corrosion and original austenite grain boundary depressions, the recrystallization of thin steel strips can be increased by high friction rolling.

[0105] Figure 5is a flow chart showing a process for implementing high friction rolling and / or surface homogenization. In an example of the present invention, determining whether a steel strip or steel product is to be subjected to high friction rolling depends on whether undesirable thermal corrosion occurs in the hot box 510. If thermal corrosion does not occur in the hot box, high friction rolling is not necessary and is not used to (1) smooth out the original austenite grain boundary depressions, (2) improve the formability of the steel product (for example, in the case of ultra-high strength weathering steel), and / or (3) improve resistance to hydrogen (H2) embrittlement. However, even if thermal corrosion does not occur in the hot box, high friction rolling can still be performed to achieve recrystallization 520 or produce a microstructure disclosed elsewhere herein. If hot corrosion occurs in the high temperature box 510, high friction rolling 530 may be performed to (1) smooth out the original austenite grain boundary depressions, (2) improve the formability of the ultra-high strength weathering steel, and / or (3) improve hydrogen (H2) embrittlement resistance by removing the original austenite grain boundary depressions and eliminating weak spots that form as defects after a 120-hour corrosion test. In one example of the present disclosure, an ultra-high strength weathering steel 550 having a smoothed pattern is produced. In another embodiment of the present disclosure, the smoothed pattern is removed to improve pitting resistance, such as pitting resistance required in automotive applications. For example, such an embodiment produces a high-strength martensitic steel 560. The smoothed pattern can be removed by surface homogenization. Figure 5 Also shown is a surface equalization process 540. The applicability of surface equalization processes will be discussed in more detail below with respect to the present disclosure. Representative examples will also be discussed in more detail below.

[0106] Ultra-high strength weathering steel

[0107] In some embodiments, the lightweight ultra-high strength weathering steel plate can be made from a molten melt. The molten melt can be processed by a twin-roll casting machine. In one example, the lightweight ultra-high strength weathering steel plate can be made by the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; (b) at a temperature above 10.0 MW / m2 heat flux solidification, produce a steel plate with a thickness of less than 2.5 mm, and before rapid cooling and / or before hot rolling (in the case of hot rolling), the steel plate is cooled to a temperature below 1080°C and above the Ar3 temperature at a cooling rate of greater than 15°C / second in a non-oxidizing atmosphere; and (c) rapid cooling to form a steel plate having a microstructure comprising at least 75 volume % of martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In one example, the lightweight ultra-high strength weathering steel plate may also be hot rolled to a rolling reduction of 15% to 50% before rapid cooling. Before rapid cooling and / or before hot rolling (in the case of hot rolling), the steel plate may be cooled to a temperature below 1100°C and above the Ar3 temperature at a cooling rate of greater than 15°C / second in a non-oxidizing atmosphere. The Ar3 temperature is the temperature at which austenite begins to transform into ferrite during cooling. In other words, the Ar3 temperature is the austenite transformation point. In each instance, nickel moves the peritectic point away from the carbon zone and / or increases the transformation temperature of the peritectic point of the steel plate composition to provide a defect-free steel plate. The effect of nickel on the corrosion index is reflected in the following formula used to determine the corrosion index calculation: copper*26.01+nickel*3.88+chromium*1.2+silicon*1.49+phosphorus*17.28–copper*nickel*7.29–nickel*phosphorus*9.1–copper*copper*33.39 (where each element is measured by weight percentage).

[0108] The steel plate examples of the present invention have nickel added to further prevent peritectic cracking while maintaining or improving hardenability. In particular, 0.5 wt % to 1.5 wt % nickel is added. The inventors believe that the addition of nickel prevents warping of the strip shell caused by volume changes in the peritectic zone during phase transformation on the casting rolls, and thereby enhances uniform heat transfer during strip solidification. The inventors believe that the addition of nickel moves the peritectic point away from the carbon zone and / or increases the transition temperature of the peritectic point of the composition, thereby forming a defect-free steel plate. Figure 4 This is shown in the phase diagram of . In particular, Figure 4The phase diagram of FIG. 1 shows the effect of each of 0.0 wt. % nickel 100, 0.2 wt. % nickel 110, and 0.4 wt. % nickel 120. Figure 4 As shown, the peritectic point P is found at the intersection of liquid phase + δ phase 90, δ + γ phase 50 and liquid phase + γ phase 60. 100 , P 110 and P 120 The increase of nickel causes the lower mass percentage of carbon (C) to shift to a higher temperature. Otherwise, in a steel strip having a high yield strength, the carbon content makes the steel strip susceptible to defects at a lower temperature. Adding nickel moves the peritectic point away from the carbon zone and / or increases the transformation temperature of the peritectic point of the steel sheet to provide a defect-free martensitic steel strip having a high yield strength.

[0109] The effect of nickel on the corrosion index is reflected in the following formula used to determine the corrosion index calculation: copper*26.01+nickel*3.88+chromium*1.2+silicon*1.49+phosphorus*17.28–copper*nickel*7.29–nickel*phosphorus*9.1–copper*copper*33.39 (where each element is calculated by weight percentage).

[0110] Table 2 below shows several composition examples of the lightweight ultra-high strength weathering steel plate of the present disclosure.

[0111] Table 2

[0112]

[0113] In Table 2, LecoN is the measured weight percent of nitrogen (N2), and CEAWS is the measured weight percent of carbon equivalent (CE).

[0114] Other elements on which hardenability is dependent have the opposite effect by shifting the peritectic point closer to the carbon region. Such elements include chromium and molybdenum, which are elements on which hardenability is dependent, but which ultimately lead to peritectic cracking. By adding nickel, hardenability can be improved and peritectic cracking can be reduced, thereby providing a fully hardened martensitic grade steel strip having high strength.

[0115] As described herein, in the composition of the present invention, the addition of nickel can be combined with a limited amount of chromium and / or molybdenum. As a result, nickel reduces any effect that these hardening elements may have on peritectic cracking. However, in one example, the additional nickel is not combined with the purposefully added boron. The purposefully added amount is 5ppm or more of boron. In other words, in one example, the addition of nickel is used in combination with a boron content that is substantially free of boron or less than 5ppm. In addition, the lightweight ultra-high strength weathering steel plate can be manufactured by further tempering the steel plate at a temperature between 150°C and 250°C for 2 to 6 hours. Tempering the steel plate can increase the elongation while minimizing the loss of strength. For example, a steel plate with a yield strength of 1250MPa, a tensile strength of 1600MPa, and an elongation of 2% can be improved to a yield strength of 1250MPa, a tensile strength of 1525MPa, and an elongation of 5% after tempering as described herein.

[0116] The lightweight ultra-high strength weathering steel plate may be a silicon-killed steel containing less than 0.008% aluminum or less than 0.006% aluminum by weight. The melt may have a free oxygen content of 5 to 70 ppm or 5 to 60 ppm. The steel plate may have a total oxygen content greater than 50 ppm. The inclusions include MnOSiO2, typically 50% of the inclusions have a particle size less than 5 microns, and the inclusions are likely to enhance the evolution of the microstructure, thereby enhancing the mechanical properties of the strip.

[0117] The melt may be solidified into a steel sheet having a thickness of less than 2.5 mm at a heat flux greater than 10.0 MW / m2 and cooled in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec to a temperature less than 1080°C and greater than the Ar3 temperature. The non-oxidizing atmosphere is an atmosphere generally composed of an inert gas such as nitrogen, argon, or a mixture thereof, wherein the oxygen content is less than about 5 wt%.

[0118] In some embodiments, the martensite in the steel plate may be formed from austenite grains having a size greater than 100 microns. In other embodiments, the martensite in the steel plate may be formed from austenite grains having a size greater than 150 microns. Rapid solidification at heat fluxes greater than 10 MW / m2 can produce an austenite grain size that responds to controlled cooling, thereby producing a defect-free plate.

[0119] The steel plate may also be hot rolled to a reduction of 15% to 50% and then rapidly cooled to form a steel plate having a microstructure comprising at least 75% martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In addition, the steel plate may be hot rolled to a reduction of 15% to 35% and then rapidly cooled to form a steel plate having a microstructure comprising at least 75% martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. In one example, the steel plate is hot rolled to a reduction of 15% to 50% and then rapidly cooled to form a steel plate having a microstructure comprising at least 90 volume % martensite or martensite plus bainite. In another example, the steel plate is hot rolled to a reduction of 15% to 50% and then rapidly cooled to form the steel plate having a microstructure comprising at least 95 volume % martensite or martensite plus bainite.

[0120] Many products can be manufactured from lightweight ultra high strength weathering ("UHSW") steel sheets of the type described herein. An example of a product that can be manufactured from lightweight ultra high strength weathering steel sheets includes steel piles. More specifically, piles or foundations for solar devices are an application example of products manufactured from lightweight ultra high strength weathering steel sheets. As used herein, "solar device" is a structure used to support solar cells, such as used in a solar power plant in a photovoltaic power plant designed to supply power to the grid. The highway industry has similar needs for foundations, such as supporting guardrails, signs, etc. The piles or steel foundations can be made from thin cast steel strips that are cold rolled using one or more rolling stands. In addition, punching systems, CNC plasma systems, and / or roller systems, etc. can also be used to provide through holes, continuous welds, local welds, and / or welds, as described below.

[0121] In one example, the steel pile includes a web and one or more flanges cold-rolled from a strip of the various carbon alloy steels described above. Fig.10 , 12 -15, 22, 24 and 26 show examples of cross-sections of UHSW steel piles cold-rolled from thin cast steel strip. Fig.10 In the embodiment, the UHSW steel pile 100 is a C-channel pile including a web 110, a first flange 120 and a second flange 130, and is an exemplary embodiment of what is referred to herein as a rolled C-channel or NXW pile. The web 110 is at a height H of the steel pile 100. 1001 and transitions to a first flange 120 at a first end 112 of the web 110 at a curved transition section 140. The web 110 also transitions to a second flange 130 at a second end 113 of the web 110 opposite to the first end 112 of the web 110 at another curved transition section 150. In this example, each curved transition section 140, 150 has a respective radius R 140 , R 150 Each radius forms an arc extending 90 degrees. Therefore, each flange 120, 130 is perpendicular to the web 110. Fig.10 In the embodiment, the first flange 120 is parallel to and opposite to the second flange 130. The first flange 120 and the second flange 130 extend from the web 110 in the same direction at a width W of the steel pile 100. 100 Extend upward.

[0122] exist Fig.10 In the embodiment, the first flange 120 and the second flange 130 include a curling structure. Specifically, for the first flange 120, the curling structure is a single curling structure including a first layer 122 and a second layer 124, wherein the first layer 122 of the curling structure of the first flange extends along the width W of the steel pile 100. 100 The direction of the transition section 140 extends from the curved transition section 140 to the teardrop-shaped transition section 160. The teardrop-shaped transition section 160 is an open bead that transitions to a closed bead. The teardrop-shaped transition section 160 extends along the width W of the steel pile. 100 and height H 100 The first layer 122 extends inwardly of the steel pile 100 toward the opposite second flange 130. In a specific example, the first layer 122 is relatively large relative to the width W of the steel pile. 100 The teardrop-shaped transition section 160 extends from the first leg 162 of the teardrop-shaped transition section 160 at an angle λ of 45 degrees. From the first leg 162, the teardrop-shaped transition section 160 extends through an arc to the second layer 124. The second layer 124 is located outside the first layer 122 at the closed bead. The second layer 124 is adjacent to the first layer 122 and extends parallel to the first layer 122. Fig.10 The second layer 124 makes the steel pile width W 100 The teardrop-shaped transition section 160 is extended to the curved transition section 140. In addition, the teardrop-shaped transition section 160 is maintained at the steel pile height H defined by the beaded section of each corresponding first flange 120 and second flange 130. 100 Inside.

[0123] Please continue to refer to Fig.10 The second flange 130, which is similar to but opposite to the first flange 120, includes a curling structure. The curling structure of the second flange includes a first layer 132 and a second layer 134, wherein the first layer 132 of the curling structure of the second flange extends along the width W of the steel pile 100. 100The direction of the transition section 150 extends from the curved transition section 150 to the teardrop-shaped transition section 170. The teardrop-shaped transition section 170 is an open bead that transitions to a closed bead as follows. The teardrop-shaped transition section 170 extends along the width W of the steel pile. 100 and height H 100 The first layer 132 extends toward the interior of the steel pile 100 toward the opposite first flange 120. In a specific example, the first layer 132 is relatively large relative to the width W of the steel pile. 100 The teardrop-shaped transition section 170 extends at an angle of 45 degrees in the direction of the first leg 172. From the first leg 172, the teardrop-shaped transition section 170 extends in an arc to the second layer 134. The second layer 134 is located outside the first layer 132 at the closed bead. The second layer 134 is adjacent to the first layer 132 and extends parallel to the first layer. Fig.10 The second layer 134 makes the steel pile width W 100 The teardrop-shaped transition section 170 is maintained at a steel pile height H defined by the hemmed sections of each respective first flange 120 and second flange 130. 100 Inside. exist Fig.10 In the example of the present invention, the thickness T of the steel plate forming the steel pile 100 is 0.062 inches (1.575 mm). Therefore, the curling section is 0.124 inches (3.15 mm). In some examples, the thickness of the steel plate forming the steel pile 100 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 100 can be 2.5 mm or less.

[0124] Fig.11 Shows Fig.10 A perspective view of the steel pile 100 at the first flange 120. The steel pile 100 has a length L 100 , wherein the web 110, the first flange 120 and the second flange 130 extend over the length L100 of the steel pile. One or more weld points 180 may be provided at the first flange 120 and the second flange 130 to keep the first layer 122, 132 in abutment with the second layer 124, 134, respectively (e.g. Fig.10 As shown). The welding point 180 can be along the length L of the steel pile. 100 The spacing is 6 inches to 24 inches. The weld points 180 can also be relative to the width W of the steel pile. 100 Centered or relative to the steel pile width W 100 In addition, the weld points 180 may be evenly spaced, or the spacing of the weld points 180 may be along the length L of the steel pile. 100 In one example, the first weld point is 0.50 inches from the first end 102 of the pile and is located along the remaining length L of the pile. 100 The weld points 180 may also be spaced evenly at 13.22 inches. 100 Centered or relative to the steel pile width W100 In one example, the weld point is located 2.68 inches from the outermost tangent line of the corresponding teardrop-shaped transition segment 160 , 170 .

[0125] Please continue to refer to Fig.11 , the first flange 120 and / or the second flange 130 may also include one or more through holes 190 and / or one or more slots 192. The through holes 190 and the slots 192 may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes 190 and / or one or more slots 192 may be provided in the web 110. This perspective view also represents Figure 12-15 Perspective view of the steel pile profile.

[0126] exist Figure 10-11 In the example of the UHSW steel pile 100, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.11 The profile of the C-shaped channel pile is generated from the width of the steel plate and thus has an overall cross-sectional material length of 50 inches or less. More specifically, the overall cross-sectional material length can be half or one-third of the width of the steel plate. At the hemmed flange, the material thickness T is maintained at each layer. Although the material thickness is maintained at T, the thickness of the flange is doubled by abutting the first layer 122, 132 and the second layer 124, 134, as shown in FIG. Fig.10 As shown in TX2. Fig.10 In FIG. 1 , the doubled flange thickness TX2 extends from the teardrop transition section 160 to the curved transition section 140. Fig.10 In the example, the height of the steel pile H 100 Greater than the width W of the steel pile 100 .exist Fig.10 In the example of the steel pile 100, the height H of the steel pile 100 is divided into two halves. 100 Axis symmetry. Fig.10 Typical UHSW steel piles may be, for example, 6×4, 6×6, 8×4.5, 8×5, 8×6, 8×8, 10×8, 10×10, 12×8, 12×10, 12×12, 14×10, 14×12, 14×14 (inches), and any shape of C-shaped slot piles (with or without corrugations) between these values. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0127] Now go to Fig.12 , wherein a C-channel UHSW steel pile 200 is shown. The C-channel pile includes a web 210, a first flange 220 and a second flange 230, and is an exemplary example of what is referred to herein as a corrugated C-channel or NCW pile. The web 210 is at a height H of the steel pile 200. 200 The web 210 extends upward and transitions to the first flange 220 at the first end 211 at a curved transition section 240. The web 210 also transitions to the second flange 230 at the second end 212 at another curved transition section 250. In this example, each curved transition section 240, 250 has a respective radius R 240 , R 250 Each radius R 240 , R 250 The flanges 220 and 230 are each still substantially perpendicular to the web 210. The web 210 also includes one or more web corrugations. Fig.12 In the embodiment, the web 210 includes a first web corrugation 213 and a second web corrugation 214. In order to form the web corrugation, the outer surface 215 of the web 210 is formed within the width W of the steel pile. 200 The outer surface 215 and each inner surface 216 are arranged along the height H of the steel pile. 200 The outer surface 215 and each inner surface 216 are perpendicular to the first flange 220 and / or the second flange 230. The outer surface 215 and each inner surface 216 form a large part of the web 210, so that the web is said to be maintained substantially perpendicular to the first flange 220 and / or the second flange 230. Each curved transition section 240, 250 extends from the corresponding first flange 220 or second flange 230 along the radius R 240 , R 250 As described above, the arc of each curved transition section 240, 250 extends more than 90 degrees to form web corrugations at the respective inner surfaces 216, and then the inner surface 216 transitions to the outer surface 215. 200 , the outer surface 215 is located at the center of the web 210. Fig.12 In the figure, the radius R 240 The arc formed by the radius R 250 The arcs formed also include the steel pile height H 200 A tangent line aligned with the outer surface 215 in the direction of.

[0128] Fig.12The web corrugations 213 and 214 of the UHSW steel pile respectively include surfaces perpendicular to the first flange 220 and the second flange 230. The web 210 is recessed from each corresponding curved transition section 240 and 250 to form two web corrugations 213 and 214. Then, each web corrugation returns to the full width W 200 , and connected by the outer surface 215 of the web 210. In contrast, as shown in the flange corrugations 222, 232 below, the corrugations can be completely formed by arcs.

[0129] Please continue to refer to Fig.12 , the first flange 220 may also include one or more corrugations. Fig.12 In the example of FIG. 2 , the first flange 220 includes a portion along the width W of the steel pile. 200 A flange corrugation 222 is formed in the center. The flange corrugation 222 is formed by a radius R extending inwardly from between the first outer surface 224 and the second outer surface 226 of the first flange 220. 222 The first lip 228 opposite to the web 210 extends from the first flange 220 at the curved transition section 260. The first lip extends along the height H of the steel pile. 200 , and is parallel to the inner surface 216 and the outer surface 215 of the web 210. The first lip 228 may also include a curved transition section 280 that transitions to a return section 229. The return section 229 extends inwardly from the first lip 228 toward the web 210. The return section 229 is parallel to the first outer surface 224 and the second outer surface 226 of the first flange 220.

[0130] Like the first flange 220, the second flange 230 may also include one or more corrugations. Fig.12 In the example of 200 A flange corrugation 232 is formed in the center. The flange corrugation 232 is formed by a radius R extending inwardly from between the first outer surface 234 and the second outer surface 236 of the second flange 230. 232 The second lip 238 opposite to the web 210 extends from the second flange 230 at the curved transition section 270. The second lip extends along the height H of the steel pile. 200 The second lip 238 may further include a curved transition section 290 that transitions to a return section 239. The return section 239 extends inwardly from the first lip 228 toward the web 210. The return section 239 is parallel to the first outer surface 234 and the second outer surface 236 of the second flange 230. Fig.12In the example of the present invention, the thickness T of the steel plate forming the steel pile 200 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 200 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 200 can be 2.5 mm or less. Fig.12 The first flange 220 and / or the second flange 230 of the UHSW steel pile 200 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 210.

[0131] exist Fig.12 In the example of the UHSW steel pile 200, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.11 The profile of the C-channel pile is generated from the width of the steel plate and therefore has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. At the corrugation, the material thickness T is maintained in each layer and transition section. Fig.12 In the example, the height of the steel pile H 200 Greater than the width W of the steel pile 200 .exist Fig.12 In the example of the steel pile 200, the height H of the steel pile 200 is divided into two halves. 200 Axis symmetry. Fig.12 Typical UHSW steel piles may be, for example, 6×4, 6×6, 8×4.5, 8×5, 8×6, 8×8, 10×8, 10×10, 12×8, 12×10, 12×12, 14×10, 14×12, 14×14 (inches), and any shape of C-shaped slot piles (with or without corrugations) between these values. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0132] Now go to Fig.13 , which shows a UHSW steel pile 300, which is a C-channel pile including a web 310, a first flange 320 and a second flange 330, and is another example of a corrugated C-channel or NCW pile. Fig.12 Similar to steel piles, Fig.13 The web 310 of the steel pile 300 is at a height H of the steel pile 300. 300 The web 310 extends upward and transitions to a first flange 320 located at the first end 311 at a curved transition section 340. The web 310 also transitions to a second flange 330 located at the second end 312 at a curved transition section 350. Each curved transition section 340, 350 has a radius R 340 , R 350 .exist Fig.13 In the embodiment, the web 310 includes a single web corrugation 313. The single web corrugation 313 is symmetrical to the height H of the steel pile. 300 This is in the same Fig.12 On the contrary, Fig.12 In the embodiment, the web 210 includes a first web corrugation 213 and a second web corrugation 214. Fig.13 The web corrugation makes the outer surface 315 of the web 310 within the width W of the steel pile. 300 The outer surface 315 and the inner surface 316 are both along the height H of the steel pile. 300 The outer surface 315 and the inner surface 316 are perpendicular to the first flange 320 and / or the second flange 330. The outer surface 315 and each inner surface 316 form a large part of the web 310, so that the web is said to be maintained substantially perpendicular to the first flange 320 and / or the second flange 330. Each curved transition section 340, 350 extends from the corresponding first flange 320 or second flange 330 along the radius R 340 , R 350 The arc formed is extended. In addition, Fig.12 on the contrary, Fig.13 The arc of the curved transition sections 340 , 350 only extends 90 degrees because the single web corrugation 313 is centrally arranged on the web 310 and is independent of the curved transition sections 340 , 350 .

[0133] Fig.13 The single web corrugation 313 of the UHSW steel pile includes an inner surface 316 perpendicular to the first flange 320 and the second flange 330. Alternatively or additionally, the inner surface 316 can be referred to as being concave relative to the web 310 or the outer surface 315 of the web 310. In contrast, as shown below in the flange corrugations 322, 332, the corrugations can be formed entirely of arcs.

[0134] Please continue to refer to Fig.13 , the first flange 320 may also include one or more corrugations. Fig.13 In the example of FIG. 3 , the first flange 320 includes a portion along the width W of the steel pile. 300A flange corrugation 322 is formed in the center. The flange corrugation 322 is formed by a radius R extending inwardly from between the first outer surface 324 and the second outer surface 326 of the first flange 320. 322 The first lip 328 opposite to the web 310 extends from the first flange 320 at the curved transition section 360. The first lip extends along the height H of the steel pile. 300 310 and is parallel to the inner surface 316 and the outer surface 315 of the web 310. The first lip 328 may also include a curved transition section 380 that transitions to a return section 329. The return section 329 extends inwardly from the first lip 328 toward the web 310. The return section 329 is parallel to the first outer surface 324 and the second outer surface 326 of the first flange 320.

[0135] Like the first flange 320, the second flange 330 may also include one or more corrugations. Fig.13 In the example of 300 A flange corrugation 332 is formed in the center. The flange corrugation 332 is formed by a radius R extending inwardly from between the first outer surface 334 and the second outer surface 336 of the second flange 330. 332 The second lip 338 opposite to the web 310 extends from the second flange 330 at the curved transition section 370. The second lip extends along the height H of the steel pile. 300 The second lip 338 may further include a curved transition section 390 that transitions to a return section 339. The return section 339 extends inwardly from the first lip 328 toward the web 310. The return section 339 is parallel to the first outer surface 334 and the second outer surface 336 of the second flange 330. Fig.13 In the example of the present invention, the thickness T of the steel plate forming the steel pile 300 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 300 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 300 can be 2.5 mm or less. Fig.13 The first flange 320 and / or the second flange 330 of the UHSW steel pile 300 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 310.

[0136] exist Fig.13In the example of the UHSW steel pile 300, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.11 The profile of the C-channel pile is generated from the width of the steel plate and therefore has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. At the corrugation, the material thickness T is maintained in each layer and transition section. Fig.13 In the example, the height of the steel pile H 300 Greater than the width W of the steel pile 300 .exist Fig.13 In the example of the steel pile 300, the height H of the steel pile 300 is divided into two halves. 300 Axis symmetry. Fig.13 Typical UHSW steel piles may be, for example, C-shaped slot piles (with or without corrugations) in the shape of 6×4, 8×4.5, 8×5, 8×6, 10×8, 12×8, 12×10, 14×10, 14×12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0137] Now please turn to Fig.14 , in which a UHSW steel pile 400 having a tubular cross-section is shown. Fig.14 The steel pile 400 is square. The steel pile 400 includes a first side wall 410, a second side wall 420, a third side wall 430, and a fourth side wall 440. The first side wall 410 is substantially parallel to the third side wall 430. The second side wall 420 is substantially parallel to the fourth side wall 440. In addition, the first side wall 410 and the third side wall 430 are substantially perpendicular to the second side wall 420 and the fourth side wall 440. "Substantially" as used in this context refers to side wall arrangements other than corrugations, as further described below. Fig.14 The height of the steel pile is 400 H 400 and width W 400The same, forming a substantially square cross-section. "Substantially" as used in this context also refers to the wall arrangement form other than corrugation. In other words, in the cross-section, the overall size of each side wall of the steel pile 400 is the same. A curved transition section is provided between each side wall. More specifically, a first curved transition section 450 is provided between the first side wall 410 and the second side wall 420; a second curved transition section 460 is provided between the second side wall 420 and the third side wall 430; a third curved transition section 470 is provided between the third side wall 430 and the fourth side wall 440; and a fourth curved transition section 480 is provided between the fourth side wall 440 and the first side wall 410. Each curved transition section 450, 460, 470 and 480 is formed by a respective radius R 450 , R 460 , R 470 and R 480 The arc formed.

[0138] Fig.14 One or more side walls of the steel pile 400 may include one or more corrugations, respectively. Fig.14 In the example of , each side wall 410, 420, 430, 440 includes a corrugation 412, 422, 432, 442, respectively. Fig.14 Each sidewall and corrugation has the same arrangement and size. Fig.14 The cross section along the longitudinal axis (X 轴 ) is symmetrical to any plane. Figure 12-13 Similar to the web corrugations of , each corrugation 412, 422, 432, 442 includes an inner surface 413, 423, 433, 443, respectively, each inner surface deviates from and is parallel to the outer surface 411, 421, 431, 441 of the side wall 410, 420, 430, 440, respectively. Fig.14 In the example of , an inclined side wall is provided to transition from the inner surface to the outer surface. Fig.14 In the embodiment, each inner surface includes opposite inclined side walls 414, 424, 434, 444. An arc can be provided to transition between each surface, between each surface and the inclined side walls, etc. As described above, the corrugations serve as reinforcements for the steel pile. Fig.14 In the embodiment, each corrugation 412, 422, 432, 442 extends inwardly. In other examples, the corrugations may extend outwardly, alternately, or form two opposite halves. In some examples, one or more side walls may include multiple corrugations, such as Fig.10 Alternatively or additionally, the corrugations may be formed entirely of arcs, e.g. Figure 12-13 The flange corrugations shown. The corrugations may be reference Fig.14 A combination of illustrated ripples and ripples formed entirely of arcs.

[0139] exist Fig.14 In the example of the UHSW steel pile 400, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.14 The profile is generated from the width of the steel plate and thus has an overall cross-sectional material length of 50 inches or less. More specifically, the overall cross-sectional material length can be half or one-third of the width of the steel plate. In addition, when formed from the steel plate, welds, rivets, laps and / or joints can be provided to close the Fig.14 The welds may be continuous welds, local welds and / or spot welds. The welds, rivets, overlaps and / or joints may be located on arcs, corrugations, inner surfaces, outer surfaces and / or inclined side walls. Fig.14 Typical UHSW steel piles can be, for example, 4×4, 6×6, 8×8, 12×12 (inches) and any shape of steel pipe (with or without corrugation) between these values.

[0140] Now please turn to Fig.15 , which shows a UHSW steel pile 500 having a tubular cross-section. Fig.14 Compared with square steel piles, Fig.15 The steel pile 500 is rectangular. Fig.14 Similar to the steel pile of FIG. 5 , the steel pile 500 includes a first side wall 510, a second side wall 520, a third side wall 530, and a fourth side wall 540. The first side wall 510 is substantially parallel to the third side wall 530. The second side wall 520 is substantially parallel to the fourth side wall 540. In addition, the first side wall 510 and the third side wall 530 are substantially perpendicular to the second side wall 520 and the fourth side wall 540. As used in this context, “substantially” refers to a side wall arrangement other than corrugation, as further described below. The height H 500 Greater than Fig.15 The width of the steel pile is 500 W 500, roughly forming a rectangular tube. "Generally" as used in this context also refers to wall arrangements other than corrugations. In other words, the overall dimensions of the first side wall 510 and the third side wall 530 are the same as the overall dimensions of the second side wall 520 and the fourth side wall 540. A curved transition section is provided between each side wall. More specifically, a first curved transition section 550 is provided between the first side wall 510 and the second side wall 520; a second curved transition section 560 is provided between the second side wall 520 and the third side wall 530; a third curved transition section 570 is provided between the third side wall 530 and the fourth side wall 540; and a fourth curved transition section 580 is provided between the fourth side wall 540 and the first side wall 510. Each curved transition section 550, 460, 570 and 580 is formed by a respective radius R 550 , R 560 , R 570 and R 580 The arc formed.

[0141] Fig.15 One or more side walls of the steel pile 500 may include one or more corrugations, respectively. Fig.15 In the example of , each side wall 510, 520, 530, 540 includes a corrugation 512, 522, 532, 542, respectively. Fig.15 , the corrugations of the first side wall 510 and the third side wall 530 are the same, while the second side wall 520 and the fourth side wall 540 include the same corrugations that are different from the first and third side walls. Fig.15 The cross section is taken along the longitudinal axis (X 轴 ) is symmetrical to any plane. Fig.10 , 12 -13 web corrugations, each corrugation 512, 522, 532, 542 comprises an inner surface 513, 523, 533, 543, respectively, each inner surface deviates from and is parallel to the outer surface 511, 521, 531, 541 of the side wall 510, 520, 530, 540, respectively. Fig.15 In the example of , inclined side walls 514, 524, 534, 544 are provided to transition from the inner surface to the outer surface. Fig.15 In the embodiment, each inner surface includes opposite inclined side walls. An arc can be provided to transition between each surface, between each surface and the inclined side walls, etc. As described above, the corrugations serve as reinforcements for the steel piles. Fig.15 In the embodiment, each corrugation 512, 522, 532, 542 extends inwardly. In other examples, the corrugations may extend outwardly, alternately, or form two opposite halves. In some examples, one or more side walls may include multiple corrugations, such as Fig.10 Alternatively or additionally, the corrugations may be formed entirely of arcs, e.g. Figure 12-13The flange corrugations shown. The corrugations may be those described above with reference to Fig.15 A combination of illustrated ripples and ripples formed entirely of arcs.

[0142] exist Fig.15 In the example of the UHSW steel pile 500, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.15 The profile is generated from the width of the steel plate, or is less than the width of the steel plate, and thus has an overall cross-sectional material length of 50 inches or less. More specifically, the overall cross-sectional material length can be half or one-third of the width of the steel plate. In addition, when formed from the steel plate, welds, rivets, overlaps, and / or joints may be provided to close the Fig.15 The welds may be continuous welds, local welds and / or spot welds. The welds, rivets, overlaps and / or joints may be located on arcs, corrugations, inner surfaces, outer surfaces and / or inclined side walls. Fig.15 Typical UHSW steel piles can be, for example, 6×4, 8×4.5, 8×5, 8×6, 10×8, 12×8, 12×10, 14×10, 14×12 (inches) and any shape of steel tube (with corrugation) between these values. In some examples, the web or height can be in the range of 6-12 inches, and the flange or width can be in the range of 2-8 inches. In other examples, the web or height can be in the range of 4-14 inches, and the flange or width can be in the range of 1-10 inches.

[0143] The shape as described above provides additional structural integrity to withstand the loads caused by the pile or steel foundation, as further described below. In addition, by utilizing the shape to improve the structural integrity, the steel pile can be produced using much thinner material than traditional galvanized I-beams. Therefore, because the cross-section of the UHSW steel pile of the present invention is reduced compared to existing piles and structural foundations, less force is required to drive this thinner material into the ground while maintaining the necessary strength and integrity.

[0144] When in use, a portion of the length of the steel pile is driven into the ground or soil to provide a structural foundation. The steel pile can be driven into the ground or soil using a rammer (e.g., a piston or hammer). The rammer can be part of a pile driver and at least driven by the pile driver. The rammer strikes or impacts the steel pile, forcing the steel pile into the ground or soil. Due to this impact, the existing steel pile may be warped or deformed under the impact of the rammer. In order to avoid warping or damage to the existing steel pile, it is necessary to keep the rotation speed (RPM) or force of the pile driver below the damage threshold. Compared with the steel piles of the prior art, the steel piles of the present invention show the ability to allow the RPM or the force applied to the steel pile to be increased without causing the steel pile to be warped or damaged, which is reflected by the strength characteristics of the steel pile. Specifically, it has been tested that the steel piles of the present disclosure allow the RPM to be increased by 25%, while the existing steel piles with comparable dimensional characteristics under this condition will suffer structural damage when driven. In addition, the existing steel piles are not weathering steel without galvanizing or zinc material surface. Therefore, existing steel piles are susceptible to corrosion due to being exposed to external conditions (including underground and soil conditions), or require additional treatments such as galvanizing. The steel piles of the present invention provide the necessary corrosion index to withstand these conditions. The combination of strength performance and corrosion performance of this product is unprecedented.

[0145] As mentioned above and Fig.10 The rolled flange of the rolled C-shaped channel shown, as described above and Figure 12-13 The corrugated web and flange of the corrugated C-shaped groove shown and as described above and Figure 14-15The bellows shown further improve the rigidity of the steel pile to prevent warping and / or be able to withstand the driving force as described above. As described herein, by providing the features and shapes of the curled C-shaped groove, the corrugated C-shaped groove and the bellows, the material thickness of the thin cast steel strip forming the ultra-high strength weathering steel pile can also be maintained at 2.5 mm or less, 2.0 mm or less, or 1.6 mm or less. The reduction of material thickness also helps to reduce the driving force required for the ultra-high strength weathering steel pile to be driven into the ground (such as soil or soil) by reducing the cross-sectional resistance between the ultra-high strength weathering steel pile and the ground. In addition, since the ultra-high strength weathering steel pile does not have an anti-corrosion coating applied separately, the coating is not easily scraped off or removed when contacting the ground during installation, and / or will not have a negative impact on the ground water and / or soil conditions when reacting with ground water and / or soil. The "coating applied separately" used in this article is a protective coating, and this protective coating can be a surface protective layer independent of the composition of steel. Examples of such separately applied protective coatings include zinc coatings, electroplated zinc coatings (e.g., hot-dip galvanizing), anti-aluminum-silicon corrosion coatings, and the like. More importantly, as described below, the piles or steel foundations of the present disclosure produce corrosion resistance without the need for a separately applied coating. By definition, weathering steel (including the ultra-high strength weathering steel disclosed herein) has inherently necessary corrosion resistance and does not require a separately applied hot-dip galvanizing process to produce such corrosion resistance. Therefore, the weathering steel of the present disclosure does not require or have a zinc coating, a hot-dip galvanizing layer, and the like.

[0146] Additional testing was conducted to evaluate the corrosion rates of UHSW steel in varying geometries, burial times, and simulated aging conditions and compared to the corrosion rates of galvanized ("HDG") steel. The results of these tests are shown in Tables 3-4 below. The materials were tested in moderately saline, low resistivity soils, also known as "highly corrosive" soils. The geometries of the materials tested included small angled piles and full-size cold-rolled C-piles. The materials designated as "applied current" received a voltage high enough to artificially induce corrosion for approximately 24 hours in an attempt to simulate the effects of a long-term installation. In this comparative analysis, the measured corrosion rates of the UHSW steel materials varied between 77% and 99% of the measured corrosion rates of the HDG steel materials.

[0147] Table 3

[0148]

[0149] Table 4

[0150]

[0151] The above comparative tests and structural capacity calculations show that steel piles produced from thin cast steel strips outperform hot-dip galvanized ("HDG") steel piles as well as existing steel piles. The UHSW steel piles of the present disclosure provide higher corrosion resistance and thinner material thickness. These improvements are maintained while maintaining the required strength and elongation properties, which enables the UHSW steel piles to resist deformation when driven into the ground. As shown by the material thickness, the weight of the UHSW steel piles is much lighter than that of existing steel piles. Specifically, compared to a steel pile consisting of a W6x7 I-beam weighing 7 pounds per foot or a W6x9 I-beam weighing 9 pounds per foot, a UHSW rolled C-channel or NXW pile with a comparable total cross-section weighs 5 pounds per foot, while a UHSW corrugated C-channel or NCW pile with a comparable cross-section weighs 3.5 pounds per foot. The UHSW steel piles of the present disclosure also have no hot-dip galvanizing layer or zinc layer. Therefore, the UHSW steel piles of the present disclosure eliminate any undesirable interaction between soil or groundwater and the zinc coating present in the HDG steel piles. Other alternatives of steel piles without a separately applied coating, such as other ungalvanized steel piles tested herein, are significantly inferior to the UHSW steel piles of the present disclosure.

[0152] Even with a zinc coating, the structural capacity and service life of HDG steel piles cannot exceed that of thinner UHSW steel piles. The time to complete corrosion of the coating is estimated by dividing the corrosion rate by the thickness. The remaining time is then multiplied by the corrosion rate of the steel to determine the final material thickness. For example, consider a 0.124-inch thick G235 sheet metal component: If the standard ratio of corrosion rates between the zinc coating and the base metal in corrosive soil conditions is used, and the corrosion rate of the zinc coating on G235 (2.1 mils / side) galvanized steel is estimated to be 0.0003 inches / year, the corrosion rate of the base steel should be approximately 0.0021 inches / year for a service life of 30 years, and the total reduction per side is calculated as follows:

[0153] (0.0021 inches / side) / (0.0003 inches / year / side) = 7 years

[0154] 0.0021 inches / year / side x 23 years x 2 sides = 0.0966 inches

[0155] The total metal loss is approximately 0.1008 inches, which will leave a 0.0232-inch thick part at the end of its useful life.

[0156] Assuming that the corrosion rate of the 0.062-inch thick UHSW material is the same as zinc, the calculation of the final thickness after the initial two years is simpler as follows:

[0157] 0.3 mil / year / side x 30 years x 2 sides = 18 mils

[0158] This resulted in a material thickness of 0.0440" after 30 years. This mild corrosion case demonstrates the material's superiority over zinc + carbon steel construction in terms of service life, and its greatly increased strength over carbon steel provides increased capability in almost any load situation.

[0159] In addition to the material property tests described above, three-point bending tests were conducted to evaluate the strength of various cross-sections of the piles disclosed herein. Specifically, the three-point bending tests showed that due to the specific characteristics of the pile shape or its cross-section, a consistent and relatively improved bending resistance was achieved. Considering that each of the piles tested was formed from the same thin cast steel strip material having a thickness of less than or equal to 1.6 mm, the relatively improved bending resistance can be attributed to the specific characteristics of the pile shape or its cross-section. The bending tests were conducted by the University of Nebraska-Lincoln.

[0160] In the test, the length of the pile under test was fixed by three hoops arranged at each end (left and right) and in the center. The pile was fixed with five bolts at both ends. Two bolts were placed on the top and bottom flanges respectively, and one bolt was attached to the web and hoop of the pile. The center hoop was attached to the pile using a single bolt at the web of the pile. Each end hoop was also attached to a separate steel plate located below the pile, and was attached in a manner that allowed rotation and allowed the pile to deflect downward. Specifically, the plate rested on two steel pipes that acted as rollers on which the plate moved. The pile was loaded using a rammer and measured using a sensor arranged between the rammer and the center hoop. Four string potentiometers were also used to measure the deflection at various points during the test. Two string potentiometers were arranged to measure the deflection at half the height of the web. These potentiometers were arranged at the bottom of the bottom flange next to the end hoop. The remaining two potentiometers measured the deflection near the center of the pile. One of them was attached to the center hoop at half the height of the flange of the pile. The other is attached directly to the pile at the same location.

[0161] As a benchmark for continuous bending resistance, Fig.13 The cross-section of the pile 300 was subjected to the above bending test. Fig.13 The pile 300 produced the measured bending resistance, but improvements were made and other shapes with higher bending resistance were developed, whose cross-sections were respectively Fig.18 , 20 Piles 600 , 700 , and 800 of 22 are shown and are further described below.

[0162] In the bending test, Fig.13 The height of the measured pile is 300 H 300 8 inches, width W 300 The material thickness T is 0.062 inches (0.1575 mm). Fig.16 Shows Fig.13 Load-deflection curves for pile 300 obtained from tests designated S2, S3 and S6. Fig.17 Shows Fig.13 Load deflection curve of pile 300 obtained from a test designated S7. In test S7, all string potentiometer attachment points were moved and attached to the bottom flange to take deflection readings. Four inclinometers were also used in each test. These inclinometers were placed on each hoop and another inclinometer was placed on the web of pile 300 adjacent to the center hoop. The inclinometers measure the rotation of the hoops and members and are used to ensure that the pile is loaded near the web. The test was started from the loading position until the pile failed without exceeding a rotation of more than 3.5 degrees at any inclinometer position. For the elastic modulus (E) of steel of 26000ksi-29000ksi (179GPa-200GPa), Figure 17-18 The slope of each of the graphs is approximately 15 inches 4 The rupture modulus corresponds to .

[0163] Table 5 below shows the Fig.13 The pile 300 corresponds to the maximum load of the specimen and the load at which nonlinearity begins.

[0164] Table 5

[0165]

[0166] Table 6 below shows the observed Fig.13 The pile 300 corresponds to the elastic stiffness of the sample. For S2–S6, the reported deformations are much higher (probably caused by the rotation of the asymmetric pile and the local deformation near the center hoop) because the deflection sensors are located on the web.

[0167] Table 6

[0168]

[0169] Table 7 below shows the Fig.13 The deflection of pile 300 corresponds to the sample at 50% load.

[0170] Table 7

[0171]

[0172] Other shapes have been developed to further improve the above mentioned properties with respect to their cross-sectional characteristics. The cross-sections of these other shapes are respectively Fig.18 , 20 The comparison test results are shown in Figure 22, piles 600, 700 and 800, respectively. Fig.19 ,21 and 23-24 and Tables 8-10, 11-13 and 14-19.

[0173] Now go to Fig.18 , which shows a UHSW steel pile 600, which is a variation of a C-shaped channel pile, including a web 610, a first flange 620 and a second flange 630. More specifically, this example is Fig.13 A variation of the corrugated C-shaped groove or NCW pile. The UHSW steel pile 600 of this example is called an M-shaped groove pile (e.g., M8x6, etc.). Fig.13 Similar to steel piles, Fig.18 The web 610 of the steel pile 600 is at a height H of the steel pile 600. 600 The web 610 extends upward and transitions to a first flange 620 located at the first end 611 at a curved transition section 640. The web 610 also transitions to a second flange 630 located at the second end 612 at a curved transition section 650. Each curved transition section 640, 650 has a radius R 640 , R 650 Each curved transition section 640, 650 is formed from the corresponding first flange 620 or second flange 630 along the radius R 640 , R 650 The arc formed extends. Fig.18 The arc of the curved transition sections 640, 650 extends 90 degrees.

[0174] exist Fig.18 In the embodiment, the web 610 includes a discontinuous portion, which is a V-shaped transition section 613. The V-shaped transition section 613 extends in the same direction as each flange 620, 630 relative to the web 610. This is similar to Fig.13 The V-shaped transition section 613 is in contrast to the single web corrugation 313 of the pile 300. 600 The apex 616 of the V-shaped transition section 613 is at the same position as the flange at the width W of the steel pile. 600 The apex 616 is offset from the outer surface 615 of the web 610 in the same direction as the direction in which the apex 616 extends. Alternatively or additionally, the apex 616 may be referred to as being recessed relative to the web 610 or recessed relative to the outer surface 615 of the web 610. The opposing sides 617, 618 of the V-shaped transition section are at an inclined angle relative to the web 610. In one example, the opposing sides 617, 618 are at right angles relative to each other.

[0175] Please continue to refer to Fig.18 , the first flange 620 may also include one or more discontinuous portions, wherein the discontinuous portions are V-shaped transition sections. Fig.18 In the example of FIG. 6 , the first flange 620 includes a portion along the width W of the steel pile. 600A V-shaped transition section 622 is formed in the middle. In some examples, the corrugations, arcs and / or V-shaped transition sections can be interchanged and / or combined on the flange and web or between the flange and web of a single pile. Fig.18 In the embodiment of the present invention, the V-shaped transition section 622 extends inwardly from the first outer surface 624 and the second outer surface 626 of the first flange 620. The first lip 628 opposite to the web 610 extends from the first flange 620 at the curved transition section 660. The first lip extends along the height H of the steel pile. 600 610 and is parallel to the outer surface 615 of the web 610. The first lip 628 may also include a curved transition section 680 that transitions to a first return section 629A. The first return section 629A extends inwardly from the first lip 628 toward the web 610. The first return section 629A is parallel to the first outer surface 624 and the second outer surface 626 of the first flange 620. A second return section 629B that is returned in the direction of the web 610 may also be provided. It should be understood that the second return section 629B may also be returned in the opposite direction (e.g., toward the opposite flange). It should also be understood that the second return section 629B may be returned at an oblique angle relative to the first return section 629A. In this example, the second return section 629B is at a 90 degree angle relative to the first return section 629A. A pile having a second return section may be more generally described as having a triple edge.

[0176] Like the first flange 620, the second flange 630 may also include one or more discontinuities, wherein the discontinuities are V-shaped transition sections. Fig.18 In the example of the second flange 630, the second flange 630 includes a width W of the steel pile. 600 A V-shaped transition section 632 is formed in the middle. In some examples, the corrugations, arcs and / or V-shaped transition sections can be interchanged and / or combined on the flange and web or between the flange and web of a single pile. Fig.18 In the embodiment of the present invention, the V-shaped transition section 632 extends inwardly from the first outer surface 634 and the second outer surface 636 of the second flange 630. The first lip 638 opposite to the web 610 extends from the second flange 630 at the curved transition section 670. The first lip extends along the height H of the steel pile. 600 The first lip 638 may further include a curved transition section 690 that transitions to a first return section 639A. The first return section 639A extends inwardly from the first lip 638 toward the web 610. The first return section 639A is parallel to the first outer surface 634 and the second outer surface 636 of the second flange 630. A second return section 639B that is returned toward the web may also be provided.

[0177] exist Fig.18In the example of the present invention, the thickness T of the steel plate forming the steel pile 600 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 600 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 600 can be 2.5 mm or less. Fig.18 The first flange 620 and / or the second flange 630 of the UHSW steel pile 600 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 610.

[0178] exist Fig.18 In the example of the UHSW steel pile 600, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.18 The profile of the M-shaped slot pile is generated from the width of the steel plate and therefore has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. At the V-shaped transition section, the material thickness T is maintained in each layer and transition section. Fig.18 In the example, the height of the steel pile H 600 Greater than the width W of the steel pile 600 .exist Fig.18 In the example of the steel pile 600, the height H of the steel pile 600 is divided into two halves. 600 Axis symmetry. Fig.18 Typical UHSW steel piles may be, for example, M6x4, M8x4.5, M8x5, M8x6, M10x8, M12x8, M12x10, M14x10, M14x12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0179] To show the bending resistance, Fig.18 The pile 600 was carried out as described above with reference to Fig.13 The same bending test as described above. In the bending test, Fig.18 The height of the measured pile is 600 H 600 8 inches, width W 600 The material thickness T is 0.062 inches (0.1575 mm). Fig.19 Shows Fig.18 Load deflection curves for pile 600 obtained from tests designated S2, S3 and S4. For tests S2-S4, sensors were placed on the web. The test results appear to indicate that the material did not yield. Instead, local load-bearing failure occurred before the material yielded. In addition, no real local buckling of the flange or any other buckling was observed. For elastic modulus (E) of steel between 26000 ksi and 29000 ksi (179 GPa-200 GPa), Fig.19 The slope of the curve in is 20.8 inches 4 Up to 18.6 inches 4 The inertia torque corresponds to .

[0180] Table 8 below shows the Fig.18 The pile 600 corresponds to the maximum load of the specimen and the load at which nonlinearity begins.

[0181] Table 8

[0182]

[0183] Table 9 below shows the elastic stiffness observed during testing.

[0184] Table 9

[0185]

[0186] Table 10 below shows the Fig.18 The deflection of pile 600 corresponds to the sample at 50% load.

[0187] Table 10

[0188]

[0189] Now go to Fig. 20 , which shows a UHSW steel pile 700, which is a C-channel pile including a web 710, a first flange 720 and a second flange 730, and is a variation of a corrugated C-channel or NCW pile. Fig.13 Similar to steel piles, Fig. 20 The web 710 of the steel pile 700 is at a height H of the steel pile 700. 700 The web 710 extends upward and transitions to a first flange 720 located at the first end 711 at a curved transition section 740. The web 710 also transitions to a second flange 730 located at the second end 712 at a curved transition section 750. Each curved transition section 740, 750 has a radius R 740 , R 750Each curved transition section 740, 750 is formed from the first flange 720 or the second flange 730 along a radius R 740 , R 750 The arc formed extends. Fig. 20 The arc of the curved transition sections 740, 750 extends 90 degrees.

[0190] exist Fig. 20 In the embodiment, the web 710 includes one or more discontinuities, which can be characterized as corrugations, which are arcs with a radius. Specifically, the first flange 720 includes a radius R 714 The first arc 714 is formed by a radius R 716 The second arc 716 is formed. Fig. 20 In the example of FIG. 7 , the first arc 714 and the second arc 716 are formed along the width W of the steel pile. 700 Spaced equally. Radius R 714、716 Extending inwardly from the outer surface 715 of the web 710 .

[0191] The first flange 720 may also include one or more discontinuities, which may be characterized as corrugations. Fig. 20 In the example of FIG. 7 , the first flange 720 includes a portion along the width W of the steel pile. 700 A flange corrugation 722 is formed in the center. The flange corrugation 722 is formed by a radius R extending inwardly from between the first outer surface 724 and the second outer surface 726 of the first flange 720. 722 The first lip 728 opposite to the web 710 extends from the first flange 720 at the curved transition section 760. The first lip extends along the height H of the steel pile. 700 , and is parallel to the inner surface 716 and the outer surface 715 of the web 710. The first lip 728 may also include a curved transition section 780 that transitions to a return section 729. The return section 729 extends inwardly from the first lip 728 toward the web 710. The return section 729 is parallel to the first outer surface 724 and the second outer surface 726 of the first flange 720.

[0192] Like the first flange 720, the second flange 730 may also include one or more discontinuities, which may be characterized as corrugations. Fig. 20 In the example of FIG. 7 , the second flange 730 includes a width W of the steel pile. 700 A flange corrugation 732 is formed in the center. The flange corrugation 732 is formed by a radius R extending inwardly from between the first outer surface 734 and the second outer surface 736 of the second flange 730. 732 The second lip 738 opposite to the web 710 extends from the second flange 730 at the curved transition section 770. The second lip extends along the height H of the steel pile. 700, and is parallel to the inner surface 716 and the outer surface 715 of the web 710. The second lip 738 may also include a curved transition section 790 that transitions to a return section 739. The return section 739 extends inwardly from the second lip 738 toward the web 710. The return section 739 is parallel to the first outer surface 734 and the second outer surface 736 of the second flange 730.

[0193] exist Fig. 20 In the example of the present invention, the thickness T of the steel plate forming the steel pile 700 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 700 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 700 can be 2.5 mm or less. Fig. 20 The first flange 720 and / or the second flange 730 of the UHSW steel pile 700 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 710.

[0194] exist Fig. 20 In the example of the UHSW steel pile 700, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig. 20 The profile of the C-shaped channel pile is generated from the width of the steel plate and therefore has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. Fig. 20 In the example, the height of the steel pile H 700 Greater than the width W of the steel pile 700 .exist Fig. 20 In the example of the steel pile 700, the height H of the steel pile 700 is divided into two halves. 700 Axis symmetry. Fig. 20 Typical UHSW steel piles may be, for example, C6x4, C8x4, C8x4.5, C8x5, C8x6, C10x8, C12x8, C12x10, C14x10, C14x12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0195] In order to show the bending resistance, multiple Fig. 20 The cross-section of the pile 700 was carried out as described above with reference to Fig.13 and 18 In the first bending test, Fig. 20 The height of the measured pile is 700 H 700 8 inches, width W 700 The material thickness T is 0.062 inches (0.1575 mm) and is called C8x4. Fig.21 Shows Fig. 20 Load deflection curves for C8x4 pile 700 obtained from tests designated S1, S2, S3, S4 and S5. For tests S1-S5, sensors were placed on the web. No local buckling was observed before failure. For steels with elastic modulus (E) of 26000 ksi-29000 ksi (179 GPa-200 GPa), Fig.21 The slopes of the curves are 6.2 inches 4 Up to 5.6 inches 4 The inertia torque corresponds to .

[0196] Table 11 below shows the Fig. 20 The C8x4 pile 700 corresponds to the maximum load of the sample and the load at which nonlinearity begins.

[0197] Table 11

[0198]

[0199] Table 12 below shows the observed Fig. 20 The C8x4 pile corresponds to the elastic stiffness of the sample of 700.

[0200] Table 12

[0201]

[0202]

[0203] Table 13 below shows the Fig. 20 The C8x4 pile 700 corresponds to the deflection of the sample at 50% load.

[0204] Table 13

[0205]

[0206] Now go to Fig. 22 , which shows a UHSW steel pile 800, which is a C-shaped groove pile including a web 815, a first flange 820 and a second flange 830, and is a corrugated C-shaped groove or NCW pile and Fig. 20A variation of the C-shaped slot pile 700. Fig. 22 The cross section of the steel pile 800 is Fig. 20 The cross-section of the steel pile 700 is basically the same, except that Fig. 22 The steel pile 800 of FIG. 8 adds the second return section 829B and 839B. In other aspects, Fig. 20 Similar to the steel pile 700, the steel pile 800 has a web 815, which is at a height H of the steel pile 800. 800 The web 815 extends upward and transitions to a first flange 820 located at the first end 811 at a curved transition section 840. The web 815 also transitions to a second flange 830 located at the second end 812 at a curved transition section 850. Each curved transition section 840, 850 has a radius R 840 , R 850 Each curved transition section 840, 850 is formed from the corresponding first flange 820 or second flange 830 along a radius R 840 , R 850 The arc formed extends. Fig. 22 The arc of the curved transition sections 840, 850 extends 90 degrees.

[0207] exist Fig. 22 In the embodiment, the web 815 includes one or more discontinuities, which can be characterized as corrugations, which are arcs with a radius. Specifically, the first flange 820 includes a radius R 814 The first arc 814 is formed by the radius R 816 The second arc 816 is formed. Fig. 22 In the example of FIG. 8 , the first arc 814 and the second arc 816 are formed along the width W of the steel pile. 800 Spaced equally. Radius R 814、816 Extending inwardly from the outer surface 810 of the web 815 .

[0208] The first flange 820 may also include one or more discontinuities, which may be characterized as corrugations. Fig. 22 In the example of FIG. 8 , the first flange 820 includes a portion along the width W of the steel pile. 800 A flange corrugation 822 is formed in the center. The flange corrugation 822 is formed by a radius R extending inward from between the first outer surface 824 and the second outer surface 826 of the first flange 820. 822 The first lip 828 opposite to the web 815 extends from the first flange 820 at the curved transition section 860. The first lip extends along the height H of the steel pile. 800810 and is parallel to the inner and outer surfaces 810 of the web 815. The first lip 828 may also include a curved transition section 880 that transitions to a first return section 829A. The first return section 829A extends inward from the first lip 828 toward the web 815. The first return section 829A is parallel to the first outer surface 824 and the second outer surface 826 of the first flange 820. A second return section 839B may also be provided. Fig.18 Similar to the second return section 629B of the pile 600, the second return section 829B can be turned back in the direction of the web 815. More specifically, the second return section 829B is turned back toward the second flange 830 at an angle relative to the first return section 829A. It should be understood that the second return section 829B can also be turned back in the opposite direction (e.g., toward the opposite flange). It should also be understood that the second return section 829B can be turned back at a 90 degree angle relative to the first return section 829A. The pile having a second return section can be more generally described as having a triple edge.

[0209] Like the first flange 820, the second flange 830 may also include one or more discontinuities, which may be characterized as corrugations. Fig. 22 In the example of the second flange 830, the second flange 830 includes a width W of the steel pile. 800 A flange corrugation 832 is formed in the center. The flange corrugation 832 is formed by a radius R extending inwardly from between the first outer surface 834 and the second outer surface 836 of the second flange 830. 832 The second lip 838 opposite to the web 815 extends from the second flange 830 at the curved transition section 870. The second lip extends along the height H of the steel pile. 800 810 and is parallel to the inner and outer surfaces 810 of the web 815. The second lip 838 may also include a curved transition section 890 that transitions to a first return section 839A. The first return section 839A extends inward from the second lip 838 toward the web 815. The first return section 839A is parallel to the first outer surface 834 and the second outer surface 836 of the second flange 830. A second return section 839B may also be provided. Fig.18 Similar to the second return section 639B of the pile 600, the second return section 839B can be turned back in the direction of the web 815. More specifically, the second return section 839B is turned back toward the second flange 830 at an angle inclined relative to the first return section 839A.

[0210] exist Fig. 22 In the example of the present invention, the thickness T of the steel plate forming the steel pile 800 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 800 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 800 can be 2.5 mm or less. Fig. 22The first flange 820 and / or the second flange 830 of the UHSW steel pile 800 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 815.

[0211] exist Fig. 22 In the example of the UHSW steel pile 800, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig. 22 The profile of the C-shaped channel pile is generated from the width of the steel plate and therefore has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. Fig. 22 In the example, the height of the steel pile H 800 Greater than the width W of the steel pile 800 .exist Fig. 22 In the example of the steel pile 800, the height H of the steel pile 800 is divided into two halves. 800 Axis symmetry. Fig. 22 Typical UHSW steel piles may be, for example, C6x4, C8x4, C8x4.5, C8x5, C8x4.5, C8x5, C8x6, C10x8, C12x8, C12x10, C14x10, C14x12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0212] To show the bending resistance, Fig. 22 The plurality of piles 800 were carried out as described above with reference to Fig.13 , 18 The same bending test as described in 20. In the first bending test, Fig. 20 The height of the measured pile is 800 H 800 8 inches, width W 800 The material thickness T is 0.062 inches (0.1575 mm) and is called C8x5. Fig.23 Shows Fig. 22Load deflection curves for C8x5 pile 800 obtained from tests designated S1, S2, S3, S4 and S5. For tests S1-S5, sensors were placed on the web. No local buckling was observed before failure. For steels with elastic modulus (E) of 26000 ksi-29000 ksi (178 GPa-200 GPa), Fig.23 The slopes of the curves in 4 Up to 13.2 inches 4 The inertia torque corresponds to .

[0213] Table 14 below shows the Fig. 22 The C8x5 pile 800 corresponds to the maximum load of the specimen and the load at which nonlinearity begins.

[0214] Table 14

[0215]

[0216] Table 15 below shows the observed Fig. 22 The C8x5 pile corresponds to the elastic stiffness of the sample of 800.

[0217] Table 15

[0218]

[0219] Table 16 below shows the Fig. 22 The C8x5 pile 800 corresponds to the deflection of the sample at 50% load.

[0220] Table 16

[0221]

[0222] In the second bending test, Fig. 22 The height of the measured pile is 800 H 800 8 inches, width W 800 The material thickness T is 0.062 inches (0.1575 mm) and is called C8x4.5. Fig.24 Shows Fig. 22 Figure 2. Load-deflection curves of a C8x4.5 pile 800 obtained from tests designated S1, S2, S3 and S4. For tests S1-S4, sensors were placed on the web. No local buckling was observed before failure.

[0223] Table 17 below shows the Fig. 22 The C8x4.5 pile 800 corresponds to the maximum load of the specimen and the load at which nonlinearity begins.

[0224] Table 17

[0225]

[0226] Table 18 below shows the observed Fig. 22 The C8x4.5 pile corresponds to the elastic stiffness of the sample of 800.

[0227] Table 18

[0228]

[0229] Table 19 below shows the Fig. 22 The C8x4.5 pile 800 corresponds to the deflection of the sample at 50% load.

[0230] Table 19

[0231]

[0232] As shown in the examples above, the shape details of steel piles made of thin cast steel strip have a great influence on the bending resistance. Fig.13 The pile 300 is compared with the corrugation 313. Fig.18 The V-shaped transition section 613 of the pile 600 significantly improves the bending resistance. Fig.13 The pile 300 is compared with the corrugation 313. Fig. 20 The multiple corrugated arcs 714, 716 of the pile 700 also improve the bending resistance. Fig. 20 Compared with the comparable pile 700, the second return section (eg Fig. 22 The second return section 838B, 839B of the pile 800 improves the bending resistance. Therefore, it has been found that these features disclosed herein further improve the performance of the steel pile made of the UHSW steel pile disclosed herein.

[0233] In addition to the performance characteristics, the bend tests described above also demonstrate the production of steel piles and corresponding shapes that have a combination of hardness and toughness that can withstand the abuse of being driven into the ground while maintaining a thickness of less than or equal to 2.5 mm, less than or equal to 2.0 mm, or even less than or equal to 1.6 mm. This reduction in thickness also provides for easier driving of steel piles into the ground, encountering much less resistance when driven into the ground than piles made from much thicker material. In other words, the UHSW steel piles and shapes of the present invention provide a product that exhibits not only hardness but also toughness at a reduced material thickness. In contrast, prior art piles would exhibit increased brittleness as hardness increased. This dynamic change is caused by Figure 25-26 This is best illustrated by the comparative example of . Fig.25 A photographic reproduction of a UHSW steel pile 300 of the present disclosure is shown after being driven into bedrock. Fig.25The steel pile 300 has Fig.13 The cross section of a steel pile 300. In contrast, Fig.26 Photographic reproductions of a steel pile 301 produced from a Class 50 wide flange beam after being driven into the same bedrock are shown. As shown in these reproductions, the UHSW steel pile does not experience any deformation on the top side of the pile, which is where force is applied to drive the pile into the ground. In contrast, the Class 50 wide flange beam exhibits significant deformation or damage on the top side of the pile, which is where force is applied to drive the pile into the ground. This demonstrates deficiencies present in prior art piles that are not exhibited by the UHSW steel piles of the present disclosure having reduced thickness.

[0234] To further illustrate the features of the UHSW steel piles of the present disclosure, the free end load and the free end deflection under the allowable point load of the UHSW steel pile (such as C8x5 described above) are shown. Figure 27-28 These properties of UHSW steel piles were compared with those of the prior art wide flange beam piles (50 grade W6x7 and 50 grade W6.9). Fig. 27 The diagram shows the allowable point load at the free end of the fixed cantilever of each pile. Fig.28 The graph shows the free end deflection of each pile at the indicated allowable point load. This data indicates the effect of potential wind loads or forces applied to the free end of a steel pile extending from the ground. In addition to the above characteristics, Figure 27-28 It is also shown that the UHSW steel piles of the present disclosure have performance comparable to or even exceeding that of prior art piles with reduced material thickness.

[0235] Figure 27-28 The properties of are reproduced in Tables 20 and 21 below. In addition, Tables 20 and 21 show the corresponding properties of additional prior art wide flange beams and additional UHSW steel piles identified in the present disclosure.

[0236] Table 20

[0237]

[0238]

[0239] Table 21

[0240]

[0241] As shown in many of the above examples, various features of the steel pile shape provide improved properties. It should be understood that the corresponding features of each steel pile shape are interchangeable and / or combinable between the steel pile examples in this article. Specifically, the above bending test shows a variety of features that improve the bending resistance of the steel pile when the bending test is performed. Examples of features that improve the bending resistance of the steel pile include V-shaped transition sections arranged on the web and / or flange and / or second return section. It is also found that the bending resistance achieved by each of these features must also be balanced over the entire cross-section of the steel pile, otherwise the steel pile of the present disclosure may be twisted, warped or damaged by local load-bearing failure (as shown in the examples above, no real local warping damage or other warping damage is shown or achieved before reaching local load-bearing failure), and thus cannot reach its full potential. In view of this problem, additional pile examples 900 and 1000 are provided below to illustrate many additional variations of steel pile shapes, which can be achieved by interchangeably and / or combining the features of many of the above pile shapes.

[0242] Fig.29 A UHSW steel pile 900 is shown. Fig.18 A variation of the M-shaped slot pile. Fig.29 The steel pile 900 includes a web 910 , a first flange 920 , and a second flange 930 . Fig.29 The web 910 of the steel pile 900 is at a height H of the steel pile 900. 900 The web 910 extends upward and transitions to a first flange 920 located at the first end 911 at a curved transition section 940. The web 910 also transitions to a second flange 930 located at the second end 912 at a curved transition section 950. Each curved transition section 940, 950 has a radius R 940 , R 950 Each curved transition section 940, 950 is formed from the first flange 920 or the second flange 930 along a radius R 940 , R 650 The arc formed extends. Fig.29 The arcs of the curved transition sections 940, 950 extend at an angle of 90 degrees.

[0243] exist Fig.29 In the embodiment, the web 910 includes a discontinuous portion, which is a V-shaped transition section 913. The V-shaped transition section 913 extends in the same direction as each flange 920, 930 relative to the web 910. The V-shaped transition section 913 is relatively large relative to the height H of the steel pile. 900 The apex 916 of the V-shaped transition section 913 is at the same position as the flange at the width W of the steel pile. 900The apex 916 is offset from the outer surface 915 of the web 910 in the same direction as the direction in which the apex 916 extends. Alternatively or additionally, the apex 916 may be referred to as being recessed relative to the web 910 or recessed relative to the outer surface 915 of the web 910. The opposing sides 917, 918 of the V-shaped transition section are at an inclined angle relative to the web 910. In one example, the opposing sides 917, 918 are at right angles relative to each other.

[0244] Please continue to refer to Fig.29 , the first flange 920 and the second flange 930 may also include one or more discontinuous portions. Fig.18 The difference is that Fig.29 The discontinuous portion of the pile 900 can be characterized as an arc-shaped corrugation, while Fig.18 In the example of , the discontinuous portion of the flange is a V-shaped transition section. Fig.29 In the example of FIG. 1 , the first flange 920 includes a portion along the width W of the steel pile. 900 A flange corrugation 922 is formed in the center. The flange corrugation 922 is formed by a radius R extending inwardly from between the first outer surface 924 and the second outer surface 926 of the first flange 920. 922 The first lip 928 opposite to the web 910 extends from the first flange 920 at the curved transition section 960. The first lip extends along the height H of the steel pile. 900 910 and is parallel to the inner and outer surfaces 915 of the web 910. The first lip 928 may also include a curved transition section 980 that transitions to a first return section 929A. The first return section 929A extends inwardly from the first lip 928 toward the web 910. The first return section 929A is parallel to the first outer surface 924 and the second outer surface 926 of the first flange 920. A second return section 939B may also be provided. The second return section 929B may be turned back in the direction of the web. More specifically, the second return section 929B is turned back toward the second flange 930 at an angle inclined relative to the first return section 929A. It should be understood that the second return section 929B may also be turned back in the opposite direction (e.g., toward the opposite flange). It should also be understood that the second return section 929B may be turned back at a 90 degree angle relative to the first return section 929A. A pile having a second return section may be more generally described as having a triple edge.

[0245] Like the first flange 920, the second flange 930 may also include one or more discontinuities, which may be characterized as corrugations. Fig.29 In the example of 900 A flange corrugation 932 is formed in the center. The flange corrugation 932 is formed by a radius R extending inwardly from between the first outer surface 934 and the second outer surface 936 of the second flange 930. 932The second lip 938 opposite to the web 910 extends from the second flange 930 at the curved transition section 970. The second lip extends along the height H of the steel pile. 900 910 and is parallel to the inner and outer surfaces 915 of the web 910. The second lip 938 may also include a curved transition section 990 that transitions to a first return section 939A. The first return section 939A extends inwardly from the second lip 938 toward the web 910. The first return section 939A is parallel to the first outer surface 934 and the second outer surface 936 of the second flange 930. A second return section 939B may also be provided. The second return section 939B may be returned in the direction of the web 910. More specifically, the second return section 939B is returned toward the second flange 930 at an angle inclined relative to the first return section 939A.

[0246] exist Fig.29 In the example of the present invention, the thickness T of the steel plate forming the steel pile 900 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 900 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 900 can be 2.5 mm or less. Fig.29 The first flange 920 and / or the second flange 930 of the UHSW steel pile 900 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 910.

[0247] exist Fig.29 In the example of the UHSW steel pile 900, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.29 The profile of the steel pile 900 is generated from the width of the steel plate and thus has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. At the V-shaped transitions and corrugations, the material thickness T is maintained at each layer and transition. Fig.29 In the example, the height of the steel pile H 700 Greater than the width W of the steel pile 700 .exist Fig.29 In the example of the steel pile 900, the height H of the steel pile 900 is divided into two halves. 900 Axis symmetry. Fig.29Typical UHSW steel piles may be, for example, 6×4, 8×4.5, 8×5, 8×6, 10×8, 12×8, 12×10, 14×10, 14×12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0248] Now go to Fig.30 The UHSW steel pile 1000 includes a web 1010, a first flange 1020 and a second flange 1030. More specifically, the steel pile is Fig.18 A variation of the corrugated M-shaped groove pile. Fig.18 Similar to steel piles, Fig.30 The web 1010 of the steel pile 1000 is at a height H of the steel pile 1000. 1000 The web 1010 extends upward and transitions to a first flange 1020 located at the first end 1011 at a curved transition section 1040. The web 1010 also transitions to a second flange 1030 located at the second end 1012 at a curved transition section 1050. Each curved transition section 1040, 1050 has a radius R 1040 , R 1050 Each curved transition section 1040, 1050 is formed from the corresponding first flange 1020 or second flange 1030 along a radius R 1040 , R 1050 The arc formed extends. Fig.30 The arc of the curved transition sections 1040, 1050 extends 90 degrees.

[0249] exist Fig.30 In the embodiment, the web 1010 includes a discontinuous portion, which is a V-shaped transition section 1013. The V-shaped transition section 1013 extends in the same direction as the first flange 1020 and the second flange 1030 relative to the web 1010. The V-shaped transition section 1013 is relatively close to the height H of the steel pile. 1000 The apex 1016 of the V-shaped transition section 1013 is at the same position as the flange at the width W of the steel pile. 1000 The apex 1016 may be offset from the outer surface 1015 of the web 1010 in the same direction as the direction in which the apex 1016 extends. Alternatively or additionally, the apex 1016 may be referred to as being recessed relative to the web 1010 or recessed relative to the outer surface 1015 of the web 1010. The opposing sides 1017, 1018 of the V-shaped transition section are at an inclined angle relative to the web 1010. In one example, the opposing sides 1017, 1018 are at right angles relative to each other.

[0250] Please continue to refer to Fig.30, the first flange 1020 may also include one or more discontinuous portions, wherein the discontinuous portions are V-shaped transition sections. Fig.30 In the example of FIG. 1 , the first flange 1020 includes a width W of the steel pile. 1000 A V-shaped transition section 1022 is formed in the middle. In some examples, the corrugations, arcs and / or V-shaped transition sections can be interchanged and / or combined on the flange and web or between the flange and web of a single pile. Fig.30 In the embodiment of the present invention, the V-shaped transition section 1022 extends inwardly from the first outer surface 1024 and the second outer surface 1026 of the first flange 1020. The first lip 1028 opposite to the web 1010 extends from the first flange 1020 at the curved transition section 1060. The first lip extends along the height H of the steel pile. 1000 1010 and is parallel to the outer surface 1015 of the web 1010. The first lip 1028 may also include a curved transition section 1080 that transitions to a first return section 1029A. The first return section 1029A extends inwardly from the first lip 1028 toward the web 1010. The first return section 1029A is parallel to the first outer surface 1024 and the second outer surface 1026 of the first flange 1020. A second return section 1039B may also be provided. The second return section 1029B may be turned back in the direction of the web 1010. More specifically, the second return section 1029B is turned back toward the first flange 1020 at an angle inclined relative to the first return section 1029A. It should be understood that the second return section 1029B may also be turned back in the opposite direction (e.g., toward the opposite flange). It should also be understood that the second return section 1029B may be turned back at an angle of 90 degrees relative to the first return section 1029A. A pile having a second switchback section can be more generally described as having a triple side.

[0251] Like the first flange 1020, the second flange 1030 may also include one or more discontinuities, wherein the discontinuities are V-shaped transition sections. Fig.30 In the example of the second flange 1030, the second flange 1030 includes a width W of the steel pile. 1000 A V-shaped transition section 1023 is formed in the middle. In some examples, the corrugations, arcs and / or V-shaped transition sections can be interchanged and / or combined on the flange and web or between the flange and web of a single pile. Fig.30 In the embodiment, the V-shaped transition section 1023 extends inwardly from the first outer surface 1034 and the second outer surface 1036 of the second flange 1030. The first lip 1038 opposite to the web 1010 extends from the second flange 1030 at the curved transition section 1070. The first lip extends along the height H of the steel pile. 1000, and is parallel to the outer surface 1015 of the web 1010. The first lip 1038 may also include a curved transition section 1090 that transitions to a first return section 1039A. The first return section 1039A extends inwardly from the first lip 1038 toward the web 1010. The first return section 1039A is parallel to the first outer surface 1034 and the second outer surface 1036 of the second flange 1030. A second return section 1039B may also be provided. The second return section 1039B may be returned in the direction of the second flange 1030. More specifically, the second return section 1039B is returned toward the second flange 1030 at an angle inclined relative to the first return section 1039A.

[0252] exist Fig.30 In the example of the present invention, the thickness T of the steel plate forming the steel pile 1000 is 0.062 inches (1.575 mm). In some examples, the thickness of the steel plate forming the steel pile 1000 can be 2 mm or less. In other examples, the thickness of the steel plate forming the steel pile 1000 can be 2.5 mm or less. Fig.30 The first flange 1020 and / or the second flange 1030 of the UHSW steel pile 1000 may also include one or more through holes and / or one or more slots. The through holes and the slots may be used to secure items such as solar devices, highway guardrails, etc. to the steel pile. Alternatively or additionally, one or more through holes and / or one or more slots may be provided in the web 1010.

[0253] exist Fig.30 In an example of the UHSW steel pile 1000, the UHSW steel pile includes a constant thickness T. The constant thickness may be less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The constant thickness T is maintained by each of the features described above. More specifically, the constant thickness is produced by a process of cold forming the UHSW steel pile from a steel plate. In one example, the width of the steel plate is 50 inches. Fig.30 The profile of the steel pile 1000 is generated from the width of the steel plate and thus has a total cross-sectional material length of 50 inches or less. More specifically, the total cross-sectional material length can be half or one-third of the width of the steel plate. At the V-shaped transition section, the material thickness T is maintained in each layer and transition section. Fig.30 In the example, the height of the steel pile H 1000 Greater than the width W of the steel pile 1000 .exist Fig.30 In the example of the steel pile 1000, the height H of the steel pile 1000 is divided into two halves. 1000 Axis symmetry. Fig.30Typical UHSW steel piles may be, for example, 6×4, 8×4.5, 8×5, 8×6, 10×8, 12×8, 12×10, 14×10, 14×12 (inches), etc. In some examples, the web or height may be in the range of 6-12 inches, and the flange or width may be in the range of 2-8 inches. In other examples, the web or height may be in the range of 4-14 inches, and the flange or width may be in the range of 1-10 inches.

[0254] As described above with respect to each of the shapes, the arc may include one or more flat segments or portions at the transition. Fig.13 The web corrugation 313 is a flat portion located between multiple true arcs, where Fig.13 The web corrugation 313 transitions from the web 310. It should be understood that the term "arc" used in this article may include one or more flat portions when it transitions. These flat portions may separate two 45° arcs separated by the flat portion to form a 90° arc. Alternatively, each arc described in this article may be a true arc. A true arc is an arc that does not contain a flat portion. In other words, in the present disclosure, an arc may be used to define a curved transition section that may be a combination of an arc and a flat portion, while a true arc may be used to define a curved transition section that has only a curvature. Each of the above arcs may also be a true arc. In the case where a flat portion needs to be included in the arc to complete or facilitate the cold roll forming process, the flat portion or transition section of the arc is usually used as the actual component of the cold roll forming. These flat portions also provide reinforcement properties for the discontinuous portion. Typically, a flat portion with a thickness of 1 times the thickness T of the material (e.g., 1 times the thickness or equal to the thickness) can be set at each transition of the arc in each of the above examples (e.g., the entrance of the arc, each 45° of the arc, the outlet of the arc, etc.). However, in some cases, the flat portion itself may give shape to the discontinuity otherwise defined herein. Specifically, as described above, Fig.13 The web corrugation 313 is only a flat portion that exceeds 1 times the thickness T of the material between the arcs. In addition, the V-shaped discontinuity also includes a flat portion, such as Fig.18The opposite sides 617, 618 of the V-shaped discontinuous portion. An arc may be additionally provided between the flat portions of the opposite sides 617, 618 of the V-shaped discontinuous portion. Therefore, it can be said that each discontinuous portion (e.g., an arc, a V-shaped transition section, a curved transition section, etc.) may include one or more flat portions that are at least 1 times the material thickness T, unless a true arc is used in the invention. Therefore, in some examples, the discontinuous portions of the web and / or flange may be a combination of a true arc, a flat portion, a true arc, a flat portion, etc., wherein the thickness of the flat portion is at least 1 times the thickness. In some examples, the thickness of the flat portion may be greater than 1 times the thickness (e.g., at least 2 times, at least 3 times, at least 4 times, at least 5 times, etc.), thereby giving additional shapes to the discontinuous portions between the true arcs of the transition section. In other examples, the discontinuous portions of the web and / or flange may be true arcs. In other examples, the discontinuous portions of the web and / or flange may be a combination of true arcs and arcs with flat portions.

[0255] The UHSW steel piles of the present disclosure also achieve improvements in packaging and transportation. Fig.31 The nested arrangement of the grooves of one example of a UHSW steel pile of the present disclosure is shown. The shapes relied upon in this particular example are those of the present disclosure. Fig.29 Shapes described and shown. It should be understood that in this nested arrangement, other shapes disclosed herein may also be relied upon. Fig.31 The nested arrangement includes three piles 1110, 1120 and 1130 arranged in a mutually overlapping and interlocking configuration. The first pile 1110 is arranged vertically with the web, the second pile 1120 is arranged inverted with the web, and the third pile 1130 is arranged vertically with the web. In the nested arrangement, one flange of the first pile overlaps with one flange of the second pile 1120, and one flange of the third pile 1130 overlaps with another flange of the second pile 1120. Additional piles can be added to the nested arrangement for transportation, and multiple sets of nested arrangements can be further stacked. The stacked nested arrangement can be set on a pallet to improve mobility. The ability to provide a nested arrangement combined with reduced material thickness improves freight efficiency by reducing the weight and space requirements of transportation. Specifically, compared with conventional piles, up to twice the number of steel piles of the present disclosure can be placed on each transport vehicle. In addition, because the nested arrangement has interlocking devices between the piles, the nested arrangement improves the stability of the transported load.

[0256] In summary, some examples of ultra-high strength weathering steel piles include cast materials having a thickness of less than or equal to 2.5 mm, less than or equal to 2.0 mm, or less than or equal to 1.6 mm. The cast material thickness is the thickness of a thin cast steel strip that is cold-rolled into a steel pile having a web and one or more flanges and a corrosion index of 6.0 or higher. The ultra-high strength weathering steel pile may also include a material yield strength of 700 to 1600 MPa, a material tensile strength of 1000 to 2100 MPa, and a material elongation between 1% and 10%. The material composition of the ultra-high strength weathering steel pile may include a nickel content sufficient to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point to form a carbon alloy steel strip having a microstructure of at least 75 volume % martensite or martensite plus bainite.

[0257] A UHSW steel pile may be a steel pile comprising a web and one or more flanges or one of the above shapes formed by cold rolling of a carbon alloy steel strip, wherein the composition of the carbon alloy steel plate comprises by weight 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is a silicon-killed steel containing less than 0.01% aluminum, wherein the carbon alloy steel strip has a microstructure comprising at least 75 volume % martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, an elongation of 1% to 10%, and has a corrosion index of 6.0 or higher. In one example, the steel pile can be formed by cold rolling of a carbon alloy steel strip having a cast thickness of less than or equal to 2.5 mm. In another example, the steel pile can be formed by cold rolling of a steel strip having a thickness of less than or equal to 2.0 mm or less than or equal to 1.6 mm. In another example, the steel pile can be formed by cold rolling of a steel plate having a thickness between 1.4 mm and 1.5 mm or a thickness of 1.4 mm or 1.5 mm. The steel pile can be a grooved pile, such as a C-shaped grooved pile, an M-shaped grooved pile, a box-shaped grooved pile, a double grooved pile, etc. Alternatively or in addition, the steel pile can be an I-shaped member, an angle steel, a structural T-shaped member, a hollow structural profile, a double angle steel, an S-shaped member, a pipe, etc. In addition, many of these members can be connected together (e.g., welded together) to form a single steel pile. It should be understood here that other products can also be made from lightweight ultra-high strength weathering steel plates. Furthermore, it should be understood herein that other products may be made from ultra high strength weathering steel that are not produced by a twin roll caster, but rather ultra high strength products may be produced by other methods.

[0258] Other examples of ultra-high strength weathering steels are provided below:

[0259] A lightweight ultra-high strength steel plate, comprising: a carbon alloy steel strip with a thickness less than or equal to 2.5 mm as cast, and the components thereof include:

[0260] (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and the steel pile is silicon killed steel containing less than 0.01% aluminum, and comprising

[0261] (ii) the remainder of iron and impurities resulting from smelting;

[0262] Among the components, nickel moves the peritectic point away from the carbon zone and / or increases the transformation temperature of the peritectic point to form a carbon alloy steel strip having a microstructure containing at least 75 volume % martensite or martensite plus bainite, a yield strength between 700 and 1600 MPa, a tensile strength between 1000 and 2100 MPa and an elongation between 1% and 10%, and is free of defects.

[0263] In one example above, the light ultra-high strength steel plate has a microstructure comprising at least 75 volume % of martensite. In another example above, the light ultra-high strength steel plate has a microstructure comprising at least 90 volume % of martensite. In another example above, the light ultra-high strength steel plate has a microstructure comprising at least 95 volume % of martensite.

[0264] In one example described above, the lightweight ultra-high strength steel sheet contains less than 5 ppm of boron.

[0265] In one example described above, the lightweight ultra-high strength steel plate contains 0.05% to 0.12% niobium.

[0266] In one of the above examples, the martensite in the steel plate is formed by austenite grains having a grain size greater than 100 micrometers.

[0267] In one of the above examples, the martensite in the steel plate is formed by austenite grains having a grain size greater than 150 microns.

[0268] In one example described above, the steel plate is also hot rolled to a reduction of 15% to 50% before rapid cooling.

[0269] In one example described above, the carbon alloy steel plate is hot rolled to a hot rolled thickness that is 15% to 35% less than the as-cast thickness before rapid cooling.

[0270] In one example described above, the steel plate is weathering steel having a corrosion index of 6.0 or higher.

[0271] A method for manufacturing a lightweight ultra-high strength weathering steel plate comprises the following steps:

[0272] (a) preparing a molten steel melt, comprising:

[0273] (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and the steel pile is silicon killed steel containing less than 0.01% aluminum, and comprising

[0274] (ii) the remainder of iron and impurities resulting from smelting;

[0275] (b) forming the melt into a casting pool supported on casting surfaces of a pair of cooled casting rolls with a nip defined therebetween;

[0276] (c) causing the casting rolls to rotate relative to each other and solidifying the melt at a heat flux greater than 10.0 MW / m2 into a steel plate having a thickness of less than 2.5 mm conveyed downwardly from the roll gap, and cooling the steel plate in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec to a temperature less than 1100°C and greater than the Ar3 temperature; and

[0277] (d) rapidly cooling to form a steel plate having a microstructure comprising at least 75 volume % martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%, wherein the nickel moves the peritectic point away from the carbon zone and / or increases the transformation temperature of the peritectic point to inhibit the formation of cracks or defects in the high-strength martensitic steel plate.

[0278] In one example of the above, the microstructure has at least 75% by volume martensite. In another example of the above, the microstructure has at least 90% by volume martensite. In another example of the above, the microstructure has at least 95% by volume martensite.

[0279] In one example described above, the carbon alloy steel plate contains less than 5 ppm boron.

[0280] In one example described above, the carbon alloy steel plate contains 0.05% to 0.12% niobium.

[0281] In one of the above examples, the martensite in the steel plate is formed by austenite grains having a grain size greater than 100 micrometers.

[0282] In one of the above examples, the martensite in the steel plate is formed by austenite grains having a grain size greater than 150 microns.

[0283] In one example described above, the steel plate is hot rolled to a hot rolled thickness that is 15% to 50% less than the as-cast thickness before rapid cooling.

[0284] In one example described above, the steel plate is hot rolled to a hot rolled thickness that is 15% to 35% less than the as-cast thickness before rapid cooling.

[0285] In one of the above examples, the high-strength steel plate is defect-free.

[0286] The present invention also discloses a steel pile, which includes a web and one or more flanges cold-rolled from a cast carbon alloy steel plate with a casting thickness of less than or equal to 2.5 mm, wherein the composition of the carbon alloy steel plate includes by weight 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is a silicon-killed steel containing less than 0.01% aluminum, wherein the carbon alloy steel plate has a microstructure containing at least 75 volume % martensite or martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, an elongation of 1% to 10%, and no defects.

[0287] In one example above, the light ultra-high strength steel plate has a microstructure comprising at least 75 volume % of martensite. In another example above, the light ultra-high strength steel plate has a microstructure comprising at least 90 volume % of martensite. In another example above, the light ultra-high strength steel plate has a microstructure comprising at least 95 volume % of martensite.

[0288] In one example described above, the carbon alloy steel plate of the steel pile contains less than 5 ppm of boron.

[0289] In one example described above, the carbon alloy steel plate of the steel pile contains 0.05% to 0.12% niobium.

[0290] In one of the above examples, the martensite in the steel pile is formed by austenite grains with a grain size greater than 100 microns.

[0291] In one of the above examples, the martensite in the steel pile is formed by austenite grains with a grain size greater than 150 microns.

[0292] In one example described above, the steel plate is also hot rolled to a reduction of 15% to 50% before rapid cooling.

[0293] In one example described above, the carbon alloy steel plate is hot rolled to a hot rolled thickness that is 15% to 35% less than the as-cast thickness before rapid cooling.

[0294] In one example described above, the carbon alloy steel plate is weathering steel having a corrosion index of 6.0 or higher.

[0295] High friction rolled high strength weathering steel

[0296] In the following example, a high friction rolled high strength weathering steel plate is disclosed. An example of an ultra-high strength weathering steel plate is made by the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is a silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; (b) solidified at a heat flux greater than 10.0 MW / m2 into a steel plate with a thickness less than or equal to 2.5 mm, and cooling the steel sheet to a temperature below 1080°C and above the Ar3 temperature in a non-oxidizing atmosphere at a cooling rate of greater than 15°C / second before rapid cooling; (c) high friction rolling the thin cast steel strip to a hot rolled thickness that is 15% to 50% less than the as-cast thickness, producing a hot rolled steel strip having essentially no, substantially no or no prior austenite grain boundary depressions and having a smeared pattern; and (d) rapid cooling to form a steel sheet having a microstructure comprising at least 75 volume % martensite or at least 75 volume % martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%. Here and elsewhere in this disclosure, elongation refers to total elongation. "Rapid cooling" refers to cooling to 100 to 200°C at a rate exceeding 100°C / second. Rapid cooling of the composition of the present invention while adding nickel can produce a steel strip containing up to 95% or more of the martensitic phase. In one example, rapid cooling forms a steel sheet having a microstructure comprising at least 95 volume % martensite or at least 95 volume % martensite plus bainite. The amount of nickel added must be sufficient to move the "peritectic point" away from the carbon zone, while in the same composition without nickel addition, the peritectic point exists in the carbon zone. Specifically, the inventors believe that the nickel in the composition helps to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point of the composition, which appears to suppress defects and produce ultra-high strength weathering steel sheets without defects.

[0297] High friction rolling of ultra-high strength weathering steel further improves the formability of ultra-high strength weathering steel. The ASTM A370 bending test standard specifies a method for measuring formability. In an embodiment, the ultra-high strength weathering steel disclosed herein can always pass the 3T 180 degree bending test. In particular, high friction rolling produces smoothing marks from the original austenite grain boundary depressions through plastic deformation under shear. These elongated surface structures characterized by smoothing patterns are beneficial to the properties of ultra-high strength weathering steel. Specifically, the formability of ultra-high strength weathering steel is improved by the smoothing pattern.

[0298] The steel strip may also contain more than 0.005% niobium or more than 0.01% or 0.02% niobium by weight. The steel strip may contain more than 0.05% molybdenum or more than 0.1% or 0.2% molybdenum by weight. The steel strip may be a silicon killed steel containing less than 0.008% aluminum by weight or less than 0.006% aluminum by weight. The molten melt may have a free oxygen content of 5 to 70 ppm. The steel strip may have a total oxygen content greater than 50 ppm. Inclusions include MnOSiO2, typically 50% of the inclusions have a particle size less than 5 microns, and the inclusions have the potential to enhance the evolution of the microstructure, thereby enhancing the mechanical properties of the strip.

[0299] The melt may be solidified into a steel strip having a thickness of less than 2.5 mm at a heat flux greater than 10.0 MW / m2 and cooled in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec to a temperature less than 1080°C and greater than the Ar3 temperature. The non-oxidizing atmosphere is an atmosphere generally composed of an inert gas such as nitrogen, argon, or a mixture thereof, wherein the oxygen content is less than about 5 wt%.

[0300] In some embodiments, the martensite in the steel strip may be derived from austenite grains having a grain size greater than 100 microns. In other embodiments, the martensite in the steel strip may be derived from austenite grains having a grain size greater than 150 microns. Rapid solidification at a heat flux greater than 10 MW / m2 can produce an austenite grain size that responds to controlled cooling after subsequent hot rolling, thereby producing a defect-free steel strip.

[0301] As described above, the steel strip of this set of examples may include a microstructure having martensite or martensite plus bainite. Martensite is formed in carbon steel by rapid cooling or quenching of austenite. Austenite has a special crystal structure called face-centered cubic (FCC). If austenite is allowed to cool naturally, then austenite will change into ferrite and cementite. However, when austenite is rapidly cooled or quenched, the face-centered cubic austenite will transform into ferrite in the form of high strain centroidal tetragonal (BCT) that is supersaturated with carbon. Shear deformation produces a large number of dislocations, which is the main strengthening mechanism of steel. During the cooling process, when the austenite reaches the martensite start temperature and the parent austenite becomes thermodynamically unstable, the martensitic reaction begins. As the sample is quenched, an increasing percentage of austenite transforms to martensite until a lower transformation temperature is reached, at which time the transformation is complete.

[0302] However, martensitic steels are prone to large depressions of the original austenite grain boundaries, which can be observed on the hot rolled outer surface of the cooled thin steel strip formed by rolling the steel under low friction conditions. The pickling or etching step amplifies these flaws, resulting in defects and delamination. High friction rolling is now introduced as an alternative method to overcome the problems of martensitic steel rolled under low friction conditions. High friction rolling produces a smoothed border pattern. The smoothed border pattern may be more generally referred to as a smoothed pattern herein. In addition, the smoothed border pattern may also be descriptively referred to as a fish scale pattern.

[0303] Just as the above-mentioned ultra-high strength weathering steel is relied upon to produce product shapes and configurations (e.g., the above-mentioned piles), many products can be produced from the high-friction rolled high-strength weathering steel plates of the type described herein. As described above, an example of a product that can be produced from high-friction rolled high-strength weathering steel plates includes steel piles. In one example, the steel pile includes a web and one or more flanges formed by cold rolling from the above-mentioned various carbon alloy steel strips. The steel pile may also include a web and one or more flanges extending over its length. When in use, a portion of the length of the steel pile is driven into the ground or soil to provide a structural foundation. A rammer (e.g., a piston or a hammer) can be used to drive the steel pile into the ground or soil. The rammer can be part of a pile driver and is at least driven by the pile driver. The rammer strikes or impacts the steel pile, forcing the steel pile to enter the ground or soil. Due to this impact, the existing steel pile may be warped or deformed under the impact of the rammer. In order to avoid warping or damage to the existing steel piles, it is necessary to keep the rotation speed (RPM) or force of the pile driver below the damage threshold. The steel piles of the present invention demonstrate the ability to allow for an increase in RPM or force applied to the steel pile without warping or damage to the steel pile, as reflected by the strength characteristics of the steel pile, as compared to prior art steel piles. Specifically, testing has demonstrated that the steel piles of the present disclosure allow for a 25% increase in RPM, where prior art steel piles of comparable dimensional characteristics would experience structural damage when driven. Additionally, prior art steel piles are not weathering steel. Therefore, prior art steel piles are susceptible to corrosion due to being exposed to external conditions, including dirt and soil conditions. The steel piles of the present invention provide the necessary corrosion index to withstand these conditions. The combination of strength performance and corrosion performance of this product is unprecedented.

[0304] In one example, the steel pile can be formed by a carbon alloy steel strip having a cast thickness of less than or equal to 2.5 mm of an example of the present invention. In another example, the steel pile can be formed by a steel strip having a thickness of less than or equal to 2.0 mm of an example of the present invention. In another example, the steel pile can be formed by a steel plate having a thickness between 1.4 mm and 1.5 mm or a thickness of 1.4 mm or 1.5 mm of an example of the present invention. The steel pile can be a groove pile, such as a C-shaped groove pile, a box-shaped groove pile, a double groove pile, etc. Alternatively or in addition, the steel pile can be an I-shaped member, an angle steel, a structural T-shaped member, a hollow structural profile, a double angle steel, an S-shaped member, a pipe, etc. In addition, many of these members can be connected together (e.g., welded together) to form a single steel pile. It should be understood here that other products can also be manufactured from high-friction rolled ultra-high strength weathering steel plates.

[0305] High-friction rolling of high-strength martensitic steel

[0306] In an embodiment of the present disclosure, a high-strength martensitic steel plate is also disclosed. The following examples of high-strength martensitic steel plates may also include weathering properties. Therefore, due to this property, the examples of high-strength martensitic steel plates of the present invention may also be referred to as ultra-high-strength weathering steel plates. Martensitic steels are increasingly used in applications requiring high strength, such as in the automotive industry. Martensitic steels provide the strength required by the automotive industry while reducing energy consumption and improving fuel economy. Martensite is formed in carbon steel by rapid cooling or quenching of austenite. Austenite has a special crystal structure known as face-centered cubic (FCC). If austenite is allowed to cool naturally, austenite will turn into ferrite and cementite. However, when austenite is rapidly cooled or quenched, face-centered cubic austenite will transform into ferrite in the form of high strain centroidal tetragonal (BCT) supersaturated with carbon. Shear deformation produces a large number of dislocations, which is the main strengthening mechanism of steel. During the cooling process, when austenite reaches the martensitic start temperature and the parent austenite becomes thermodynamically unstable, the martensitic reaction begins. As the sample is quenched, a greater and greater percentage of the austenite transforms to martensite until a lower transformation temperature is reached, at which point the transformation is complete.

[0307] However, martensitic steels are prone to large prior austenite grain boundary depressions, which can be observed on the hot rolled outer surface of a cooled thin strip formed by rolling the steel under low friction conditions. The pickling or etching step amplifies these defects, resulting in defects and delamination. High friction rolling has now been introduced as an alternative method to overcome the problems of martensitic steels rolled under low friction conditions, but it has also been found that high friction rolling can produce an undesirable surface finish. In particular, high friction rolling produces a smoothed boundary pattern and an uneven surface finish. The smoothed boundary pattern may be more generally referred to as a smoothed pattern herein. In addition, the smoothed boundary pattern may also be descriptively referred to as a fish scale pattern. The uneven surface finish with a smoothed pattern becomes prone to retaining acid and / or causing excessive corrosion (for example, when the thin strip is subjected to subsequent acid etching), thereby resulting in excessive pitting. With this in mind, some steel strips or products, such as martensitic steel sheets for automotive applications, require additional surface treatment to provide a surface that eliminates the smear pattern and / or uneven surface finish.

[0308] In order to reduce or eliminate the smearing pattern and / or uneven surface finish, the thin steel strip is subjected to surface homogenization after hot rolling. Examples of surface homogenization include sandblasting, such as by grinding wheels, shot peening, sandblasting, wet sandblasting, other pressurized application of abrasives, and the like. A specific example of surface homogenization includes ecological pickling surface (referred to herein as "EPS"). Other examples of surface homogenization include forcibly applying abrasive media to the surface of the steel strip to homogenize the surface of the steel strip. Pressurized components can also be used to achieve forced application. For example, a fluid can push the abrasive media. The fluid used in this article includes liquids and air. Alternatively or in addition, mechanical devices can be used to achieve forced application. The surface homogenization is performed after the thin cast steel strip reaches room temperature. In other words, the surface homogenization is not performed in an online process using a hot rolling mill. The surface homogenization can be performed at a location separate from or offline from the hot rolling mill and / or the twin-roll continuous caster. In some examples, the surface homogenization can be performed after coiling.

[0309] The surface homogenization treatment used in this article changes the surface so that it has no smearing pattern or eliminates the smearing pattern. The surface of the thin steel strip without a smearing pattern or in which the smearing pattern has been eliminated is a surface without any surface pitting after a 120-hour corrosion test. In the 120-hour corrosion test, the sample that has not been subjected to the surface homogenization treatment has cracks due to surface corrosion after 24 hours. Figure 6 is an image showing the surface of a high friction hot rolled steel strip homogenized using EPS. Figure 7 is an image showing a high friction hot rolled steel strip surface having a smeared pattern that has not been subjected to surface leveling. As described above, unless the smeared pattern is removed by surface leveling, the smeared pattern will retain acid during acid etching and thus be susceptible to excessive pitting and / or corrosion. In general, a surface subjected to surface leveling as used herein is a surface without a smeared pattern previously formed by high friction rolling conditions.

[0310] After hot rolling, the hot rolled thin steel strip is cooled. In each embodiment, the steel strip undergoes a surface homogenization treatment after cooling. It should be understood that cooling can be accomplished by any known means. In some cases, when cooling the thin steel strip, the thin steel strip is cooled to a temperature equal to or lower than the martensite start transformation temperature MS, thereby forming martensite from the original austenite in the thin steel strip.

[0311] One embodiment of a high strength martensitic steel plate is made by the following steps: (a) preparing a molten steel melt comprising: (i) by weight, 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and being silicon killed steel containing less than 0.01% aluminum, and (ii) the balance being iron and impurities resulting from melting; (b) solidifying at a heat flux greater than 10.0 MW / m2 into a steel plate having a thickness less than or equal to 2.5 mm, and heating in a non-oxidizing atmosphere at a high temperature before rapid cooling; Cooling the steel sheet to a temperature below 1080°C and above the Ar3 temperature at a cooling rate of 15°C / second; (c) high-friction rolling the thin cast steel strip to a hot-rolled thickness that is 15% to 50% less than the as-cast thickness to produce a hot-rolled steel strip without prior austenite grain boundary depressions; (d) rapid cooling to form a steel sheet having a microstructure comprising at least 75 volume % martensite or at least 75 volume % martensite plus bainite, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%; and (e) surface homogenizing the high-friction hot-rolled steel strip to produce a high-friction hot-rolled steel strip having a pair of opposing high-friction hot-rolled homogenized surfaces without a smearing pattern. Here and elsewhere in the present disclosure, elongation refers to total elongation. "Rapid cooling" refers to cooling to 100 to 200°C at a rate exceeding 100°C / second. Rapid cooling of the composition of the present invention while adding nickel can produce a steel strip containing up to 95% or more of the martensitic phase. In one example, rapid cooling forms a steel sheet having a microstructure containing at least 95% by volume martensite or at least 95% by volume martensite plus bainite. The amount of nickel added must be sufficient to move the "peritectic point" away from the carbon zone, while in the same composition without the addition of nickel, the peritectic point exists in the carbon zone. Specifically, the inventors believe that the nickel in the composition helps to move the peritectic point away from the carbon zone and / or increase the transformation temperature of the peritectic point of the composition, which appears to suppress defects and produce defect-free high-strength martensitic steel sheet.

[0312] Other variations of examples of high-friction rolled high-strength martensitic steel are described below. In some examples, the steel strip may include a pair of opposing high-friction hot-rolled homogenized surfaces that are substantially free of prior austenite grain boundary depressions and smear patterns. In another example, the steel strip may also include a pair of opposing high-friction hot-rolled homogenized surfaces that are substantially free of prior austenite grain boundary depressions and smear patterns. In each of these examples, the surface may have a surface roughness (Ra) of no more than 2.5 microns.

[0313] In some examples, the thin steel strip can be further tempered at a temperature between 150°C and 250°C for 2 to 6 hours. Tempering the steel strip can improve elongation while minimizing strength loss. For example, a steel strip having a yield strength of 1250 MPa, a tensile strength of 1600 MPa, and an elongation of 2% can be improved to a yield strength of 1250 MPa, a tensile strength of 1525 MPa, and an elongation of 5% after tempering as described herein.

[0314] The steel strip may also contain more than 0.005% niobium or more than 0.01% or 0.02% niobium by weight. The steel strip may contain more than 0.05% molybdenum or more than 0.1% or 0.2% molybdenum by weight. The steel strip may be a silicon killed steel containing less than 0.008% aluminum by weight or less than 0.006% aluminum by weight. The molten melt may have a free oxygen content of 5 to 70 ppm. The steel strip may have a total oxygen content greater than 50 ppm. Inclusions include MnOSiO2, typically 50% of the inclusions have a particle size less than 5 microns, and the inclusions have the potential to enhance the evolution of the microstructure, thereby enhancing the mechanical properties of the strip.

[0315] The melt may be solidified into a steel strip having a thickness of less than 2.5 mm at a heat flux greater than 10.0 MW / m2 and cooled in a non-oxidizing atmosphere at a cooling rate greater than 15°C / sec to a temperature less than 1080°C and greater than the Ar3 temperature. The non-oxidizing atmosphere is an atmosphere generally composed of an inert gas such as nitrogen, argon, or a mixture thereof, wherein the oxygen content is less than about 5 wt%.

[0316] In some embodiments, the martensite in the steel strip may be derived from austenite grains having a grain size greater than 100 microns. In other embodiments, the martensite in the steel strip may be derived from austenite grains having a grain size greater than 150 microns. Rapid solidification at a heat flux greater than 10 MW / m2 can produce an austenite grain size that responds to controlled cooling after subsequent hot rolling, thereby producing a defect-free steel strip.

[0317] High friction rolled steel sheets can be used for hot stamping applications. Typically, steel sheets for hot stamping applications are stainless steel components or require aluminum-silicon corrosion resistant coatings. In hot stamping applications, corrosion protection layers are required while maintaining high strength properties and favorable surface structural features. The high friction rolled composition of the present invention achieves the desired performance without relying on stainless steel components or providing aluminum-silicon corrosion resistant coatings. On the contrary, as shown in the various examples above, the high friction rolled composition of the present invention relies on a mixture of nickel, chromium and copper to improve corrosion resistance. In hot stamping applications, the high friction rolled steel sheet is subjected to austenitizing conditions at a temperature of 900°C to 930°C for 6 minutes to 10 minutes. In one example, the high friction rolled steel sheet is subjected to austenitizing conditions at 900°C for 6 minutes. In another example, the high friction rolled steel sheet is subjected to austenitizing conditions at 900°C for 10 minutes. In another example, the high friction rolled steel sheet is subjected to austenitizing conditions at 900°C for 10 minutes. In another example, the high friction rolled steel sheet is subjected to austenitizing conditions at 930°C for 6 minutes. In another example, the high friction rolled steel plate was subjected to austenitizing condition at 930°C for 10 minutes. Table 22 below shows that the properties of high friction rolled steel plate for hot stamping applications maintain a minimum tensile strength above 1500 MPa, a minimum yield strength above 1100 MPa, and a minimum elongation above 3%.

[0318] Table 22

[0319] Austenitizing conditions Tensile strength (MPa) Yield Strength(MPa) Elongation(%) 900℃, 6 minutes 1546.98 1155.06 7.3 900℃, 6 minutes 1576.65 1154.37 7.0 900℃,10min 1591.14 1168.86 6.4 900℃,10min 1578.03 1152.30 6.6 930℃, 6 minutes 1566.30 1146.09 7.3 930℃, 6 minutes 1566.99 1178.52 6.5 930℃,10min 1509.03 1109.52 6.6 930℃,10min 1521.45 1129.53 6.4

[0320] In these examples, the steel sheet for hot stamping application may include the composition of any one of the examples of the steel sheet disclosed above, but is an unquenched steel sheet. Specifically, the steel sheet for hot stamping application may be manufactured by the following steps: (a) preparing a molten steel melt, which contains: (i) by weight, 0.20% to 0.40% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and is silicon-killed steel containing less than 0.01% aluminum, and contains (ii) the balance of iron and impurities caused by melting; (b) at a temperature above 10.0 (c) high friction rolling of the thin cast steel strip to a hot rolled thickness that is 15% to 50% less than the as-cast thickness, producing a hot rolled steel strip having essentially no, substantially no, or no prior austenite grain boundary depressions and a smeared pattern; and (d) cooling at a rate of less than 100°C / second to form a steel sheet having a microstructure that is primarily bainite. In other words, the steel sheet for hot stamping applications can be any of the examples of steel sheets disclosed above, but the steel sheet has not been rapidly cooled, and therefore has not formed a microstructure that is essentially or substantially martensite or martensite plus bainite. Instead, the steel sheet for hot stamping applications is cooled at a rate of less than 100°C / second.

[0321] Hot rolling (including low friction hot rolling and high friction hot rolling)

[0322] The hot rolling relied upon in the above examples of the present disclosure, more specifically low friction rolling and high friction rolling, will be further described below. The concepts described below can be applied to the examples provided above as needed to achieve the characteristics of each corresponding example. Generally, in each hot rolling example, the strip is hot rolled by a hot rolling mill to reduce the as-cast thickness before cooling the strip (e.g., cooling to a temperature at which austenite in the steel transforms to martensite in a specific embodiment). In specific cases, the hot solidified strip (cast strip) can be passed through the hot rolling mill at an entry temperature above 1050°C (in some cases up to 1150°C). After the strip leaves the hot rolling mill, in certain exemplary cases, the strip is cooled to a temperature at which austenite in the steel transforms to martensite by cooling to a temperature equal to or below the martensite start transformation temperature MS. In some cases, the temperature is ≤600°C, where the martensite start transformation temperature MS depends on the specific composition. Cooling can be achieved by any known method using any known mechanism, including the method described above. In some cases, cooling is fast enough to avoid the appearance of significant ferrite, which is also affected by the composition. For example, in this case, the cooling is configured to reduce the temperature of the strip at a rate of approximately 100° C. to 200° C. per second.

[0323] Hot rolling is performed using one or more pairs of opposing work rolls. Work rolls are generally used to reduce the thickness of a substrate, such as a plate or strip. This is achieved by passing the substrate through a gap provided between a pair of work rolls, which gap is smaller than the thickness of the substrate. This gap is also known as the roll gap. During hot working, forces are applied to the substrate by the work rolls, thereby exerting a rolling force on the substrate to reduce the thickness of the substrate by the desired amount. During this period, friction is generated between the substrate and each work roll as the substrate passes through the gap. This friction is known as roll bite friction.

[0324] Traditionally, it is desirable to reduce the bite friction during hot rolling of steel plates and strips. By reducing the bite friction (and thereby reducing the coefficient of friction), rolling loads and roll wear can be reduced, thereby extending the service life of the machine. Various techniques have been used to reduce roll bite friction and reduce the coefficient of friction. In certain exemplary cases, the thin steel strip is lubricated to reduce the roll bite friction. Lubrication can take the form of a lubricating oil that is applied to the rolls and / or the thin steel strip, or an oxide scale is formed along the outside of the thin steel strip prior to hot rolling. By using lubrication, hot rolling can be carried out under low friction conditions, where the coefficient of friction (μ) of the roll bite is less than 0.20.

[0325] In one example, the friction coefficient (μ) is determined based on a hot rolling model developed by HATCH for a specific set of work rolls. Figure 8, which provides the percentage reduction in thickness of a thin steel strip along the X-axis and the specific force "P" along the Y-axis in units of kN / mm. The specific force P is the normal (perpendicular) force applied by the work rolls to the substrate. The model includes five (5) curves, each representing a friction coefficient, and provides the relationship between rolling reduction and work roll force. For each friction coefficient, the expected work roll force is obtained based on the measured rolling reduction. In operation, during hot rolling, a target friction coefficient is preset by adjusting the lubrication of the work rolls, a target rolling reduction is set by the desired strip thickness at the mill exit to meet specific customer order requirements, and the actual work roll force is adjusted to achieve the target rolling reduction. Figure 8 The typical forces required to achieve a target roll reduction for a specific coefficient of friction are shown.

[0326] In certain exemplary cases, the coefficient of friction is equal to or greater than 0.20. In other exemplary cases, the coefficient of friction is equal to or greater than 0.25, equal to or greater than 0.268, or equal to or greater than 0.27. It should be understood that under certain conditions for austenitic steel (the steel alloy used in the examples shown in the figures) (the steel is austenitic during hot rolling, but forms martensite with prior austenite grains and prior austenite grain boundary depressions after cooling), these friction coefficients are sufficient to at least substantially or essentially eliminate the austenite grain boundary depressions of the hot rolled surface and produce elongated surface features that are plastically formed by shearing. As previously described, under certain conditions, a variety of factors or parameters can be varied to obtain the desired friction coefficient. It should be noted that for the aforementioned values ​​of friction coefficient, for a substrate having a thickness of 5 mm or less before hot rolling, the normal force applied to the substrate during hot rolling can be 600-2500 tons when the substrate enters the work roll pair and translates or advances at a speed of 45-75 meters per minute, wherein the temperature of the substrate entering the work roll is greater than 1050° C., and in some cases up to 1150° C. For these friction coefficients, the diameter of the work roll is 400 to 600 mm. Of course, variations outside of these parameter ranges can be used as desired to achieve different friction coefficients to obtain the hot rolled surface characteristics described herein.

[0327] In one example, hot rolling was carried out under high friction conditions, wherein the friction coefficient was 0.25, the rolling speed was 60 m / min, the work roll force was about 820 tons, and the rolling reduction was 22%. In another example, hot rolling was carried out under high friction conditions, wherein the friction coefficient was 0.27, the rolling speed was 60 m / min, the work roll force was about 900 tons, and the rolling reduction was 22%.

[0328] The hot rolling of the thin steel strip relied upon in the embodiments of the present disclosure is performed when the thin steel strip is at a temperature above the Ar3 temperature. The Ar3 temperature is the temperature at which austenite begins to transform into ferrite during cooling. In other words, the Ar3 temperature is the austenite transformation point. The Ar3 temperature is several degrees lower than the A3 temperature. Alpha ferrite is formed below the Ar3 temperature. Fig. 9 These temperatures are shown in the exemplary CCT diagram of Fig. 9 In the figure, A3 170 represents the upper limit temperature of the stability end point of ferrite in equilibrium. Ar3 is the upper limit temperature of the stability end point of ferrite during cooling. More specifically, the Ar3 temperature is the temperature at which austenite begins to transform into ferrite during cooling. In other words, the Ar3 temperature is the austenite transformation point. In contrast, A1 180 represents the lower limit temperature of the stability end point of ferrite in equilibrium.

[0329] Please continue to refer to Fig. 9 , the ferrite curve 220 represents the transformation temperature for producing a microstructure of 1% ferrite, the pearlite curve 230 represents the transformation temperature for producing a microstructure of 1% pearlite, the austenite curve 250 represents the transformation temperature for producing a microstructure of 1% austenite, and the bainite curve (Bs) 240 represents the transformation temperature for producing a microstructure of 1% bainite. As described in more detail above, the martensite start transformation temperature MS is represented by the martensite curve 190, at which temperature martensite begins to form from prior austenite in the thin steel strip. Fig. 9 Also shown is a 50% martensite curve 200, which represents a microstructure having at least 50% martensite. Fig. 9 A 90% martensite curve 210 is shown, which represents a microstructure having at least 90% martensite.

[0330] exist Fig. 9 In the exemplary CCT diagram shown, the martensite start transformation temperature MS190 is shown. When passing through the cooler, the austenite in the steel strip is transformed into martensite. Specifically, in this case, cooling the strip to below 600°C causes the transformation of coarse austenite, wherein dispersed fine cementite is precipitated in the martensite.

[0331] Although the present invention is shown and described above by way of illustrative embodiments and with reference to the accompanying drawings, these contents are exemplary only and not restrictive. It should be understood that only some exemplary embodiments are shown and described herein, and all changes and modifications falling within the spirit of the present invention as described in the following claims should be protected. By reading this specification, the additional features of the present invention will become apparent to those skilled in the art. Various modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A cold-formed ultra-high strength weathering steel pile, wherein the cold-formed ultra-high strength weathering steel pile is made of a continuously cast hot-rolled steel strip, and the cold-formed ultra-high strength weathering steel pile comprises: A cold-formed web and a pair of opposing cold-formed flanges, each flange having a discontinuous portion formed therein, the ultra-high strength weathering steel pile having a thickness of 2.5 mm or less, and comprising, by weight: (i) 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and the steel pile is silicon killed steel containing less than 0.01% aluminum, and comprises (ii) the remainder of iron and impurities resulting from smelting; The pile has a microstructure of at least 75% by volume martensite and has a corrosion index of 6.0 or higher, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%.

2. The cold-formed ultra-high strength weathering steel pile according to claim 1, wherein the discontinuous portion of the web is a V-shaped transition portion.

3. The cold-formed ultra-high strength weathering steel pile of claim 2, wherein the V-shaped transition portion is centered on the web relative to the height of the pile, and the pile forms an M-shaped groove.

4. The cold-formed ultra-high strength weathering steel pile of claim 3, wherein the discontinuous portion of each flange of the pair of opposing flanges is a V-shaped transition portion.

5. The cold-formed ultra-high strength weathering steel pile of claim 4, wherein the V-shaped transition portion of each flange of the pair of opposing flanges is centered on each flange relative to the width of the pile.

6. The cold-formed ultra-high strength weathering steel pile of claim 1, wherein the web of the pile extends to a height between 4 and 12 inches, and each of a pair of opposing flanges of the pile extends to a width between 2 and 8 inches.

7. The cold-formed ultra-high strength weathering steel pile of claim 2, wherein the discontinuous portion of each flange of the pair of opposing flanges is an arc-shaped corrugation.

8. The cold-formed ultra-high strength weathering steel pile of claim 2, wherein the discontinuous portion of each flange of the pair of opposing flanges is a true arc-shaped corrugation.

9. The cold-formed ultra-high strength weathering steel pile of claim 7, wherein the arc of each flange of the pair of opposing flanges is centered on each flange relative to the width of the pile.

10. The cold-formed ultra-high strength weathering steel pile of claim 7, wherein the arc shape of each flange of the pair of opposing flanges includes one or more flat portions having a thickness of at least 1 times.

11. The cold-formed ultra-high strength weathering steel pile of claim 2, further comprising a triple edge.

12. The cold-formed ultra-high strength weathering steel pile of claim 1, wherein the thickness is 2.0 mm or less.

13. The cold-formed ultra-high strength weathering steel pile of claim 1, wherein the thickness is 1.6 mm or less.

14. The cold-formed ultra-high strength weathering steel pile of claim 1, wherein the discontinuous portion of the web is one or more arc-shaped corrugations.

15. The cold-formed ultra-high strength weathering steel pile of claim 1, wherein the discontinuous portion of the web is one or more true arc-shaped corrugations.

16. The cold-formed ultra-high strength weathering steel pile of claim 14, wherein the arcuate shape includes one or more flat portions having at least 1 times the thickness.

17. The cold-formed ultra-high strength weathering steel pile of claim 16, wherein the web comprises two corrugations which are arc-shaped and are equally spaced apart on the web relative to the height of the pile.

18. The cold-formed ultra-high strength weathering steel pile of claim 16, wherein the discontinuous portion of each flange is one or more arc-shaped corrugations.

19. A cold-formed ultra high strength weathering steel pile as claimed in claim 18, wherein the one or more corrugations of the flange are centred on each flange relative to the width of the pile.

20. The cold-formed ultra-high strength weathering steel pile of claim 19, wherein the web of the pile extends to a height between 4 and 12 inches, and each of a pair of opposing flanges of the pile extends to a width between 2 and 8 inches.

21. The cold-formed ultra-high strength weathering steel pile of claim 19, wherein each flange includes a turned-back lip.

22. The cold-formed ultra-high strength weathering steel pile of claim 21, wherein each returned lip is returned at an angle oblique to the web and the corresponding flange.

23. The cold-formed ultra-high strength weathering steel pile of claim 22, wherein the web of the pile extends to a height between 4 and 12 inches and each of a pair of opposing flanges of the pile extends to a width between 2 and 8 inches.

24. A solar energy device comprising: The cold-formed ultra-high strength weathering steel pile is made of a continuously cast hot-rolled steel strip, and the cold-formed ultra-high strength weathering steel pile comprises: A cold-formed web and a pair of opposing cold-formed flanges, each flange having a discontinuous portion formed therein, the ultra-high strength weathering steel pile having a thickness of 2.5 mm or less, and a composition comprising: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, 0.5% to 1.5% nickel, and the steel pile is silicon killed steel containing less than 0.01% aluminum, and comprising (ii) the remainder of iron and impurities resulting from smelting; The cold-formed ultra-high strength weathering steel pile has a microstructure of at least 75% by volume of martensite and has a corrosion index of 6.0 or higher, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%; and Part of the length of the cold-formed ultra-high strength weathering steel pile is driven into the ground, and one or more solar cells are supported above the ground by the cold-formed ultra-high strength weathering steel pile.

25. A cold-formed ultra-high strength weathering steel pile having a microstructure of at least 75% by volume martensite and comprising: a cold-formed web and a pair of opposing cold-formed flanges, a discontinuous portion being formed in each flange, the ultra-high strength weathering steel pile having a thickness of 2.5 mm or less, a corrosion index of 6.0 or more, a yield strength of 700 to 1600 MPa, a tensile strength of 1000 to 2100 MPa, and an elongation of 1% to 10%, The components of the cold-formed ultra-high strength weathering steel piles include: (i) by weight, 0.20% to 0.35% carbon, less than 1.0% chromium, 0.7% to 2.0% manganese, 0.10% to 0.50% silicon, 0.1% to 1.0% copper, less than or equal to 0.12% niobium, less than 0.5% molybdenum, and the steel pile is a silicon-killed steel containing less than 0.01% aluminum and a nickel content sufficient to move the peritectic point away from the carbon region and / or to increase the transformation temperature of the peritectic point to form a carbon alloy steel strip having a microstructure of at least 75 volume % martensite, and (ii) The balance is iron and impurities resulting from melting.

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